# Getting Started with Codex — New Agent Walkthrough

Standard edition v4 • October 18, 2026 • Prepared by Dexy for Annie’s agents

## How to use this guide with your ChatGPT

You can start in ChatGPT in your web browser before installing anything. This Markdown (.md) file is a text document containing the guide. Attaching it gives ChatGPT a reference for this conversation; it does not install Codex or automatically change your account settings.

1. Save **codex-setup-manual.md** from your coordinator's message to your computer, somewhere you can find it, such as Downloads.
2. Open **https://chatgpt.com** in your browser and sign in with your own subscribed account.
3. Start a new chat.
4. Use the attachment control beside the message box (often a **+** or paperclip), choose the file upload option, and select **codex-setup-manual.md**. Wait until the file appears attached.
5. Paste the following message and send it with the file:

> Read the attached Codex setup guide. Help me follow it one step at a time, using plain language. First ask whether I use Windows or Mac and what screen I am currently seeing. Wait for my answer before giving the next step. Help me use my existing ChatGPT Plus account and start with a local practice folder. If I see a GitHub prompt, ask for the exact wording or a screenshot before telling me what to click. If the guide differs from the current official OpenAI instructions, explain the difference and use the current instructions. After setup, help me create and open START-HERE.md, then help me report my setup status to your coordinator.

6. Answer ChatGPT's questions and follow one step at a time. Keep that browser chat open while installing and using the desktop app.

If the upload control is unavailable or the file is rejected, open the .md file in Notepad (Windows) or a text editor (Mac), copy its contents into the chat, and send the same message above, replacing “attached” with “pasted.”

You do not need to put this guide in Custom Instructions or create a custom GPT. You can also read it directly and follow the steps yourself.

[Official guidance on attaching files as chat context](https://learn.chatgpt.com/docs/use-chatgpt)

## Your first-session checklist

- [ ] Install the official desktop app for your computer.
- [ ] Sign in with the account that has your ChatGPT Plus membership.
- [ ] Choose Codex and open a local Agent Practice folder.
- [ ] Complete the practice task and open the saved file.
- [ ] Open the project materials your coordinator provides and read the starting instructions.

If GitHub signup is blocking you, go straight to Step 4. If your screen differs, use the troubleshooting table rather than guessing.

## Account and plan check

Start with your own ChatGPT account at https://chatgpt.com. If you do not have an account, follow the account creation flow. Keep track of your sign-in method.

Free accounts currently have some Codex access, subject to rollout and limits. Annie’s standard paid path uses Plus, currently listed at $20/month. To upgrade, use your ChatGPT account’s plan or upgrade option, compare plans, then review the price, currency, renewal and cancellation terms in checkout before completing the purchase yourself. If you already subscribe, use that account. See https://learn.chatgpt.com/docs/pricing for current details.

## Start here

This guide assumes your $20 membership is **ChatGPT Plus**. OpenAI currently lists Plus at $20/month and includes Codex access with usage limits. Use your own subscribed ChatGPT account. You do not need to buy another subscription just to follow this setup. [Plan details](https://learn.chatgpt.com/docs/pricing)

**You can begin with files on your computer without creating a GitHub account.** GitHub is an online service for storing and collaborating on software projects. The documented Codex Cloud setup connects GitHub repositories; that is a different setup path from opening a local folder. [Cloud setup](https://learn.chatgpt.com/docs/cloud)

## 1. Download and install

Open the official installation page for your computer:

- **Windows:** [Official Windows desktop installation guide](https://learn.chatgpt.com/docs/windows/windows-app). Click its ChatGPT desktop app download link and follow the Microsoft Store installation prompts. Open the installed app from Start.
- **Mac:** [Official desktop app page](https://learn.chatgpt.com/docs/app). Follow its download link and install the app, then open it from Applications. The page currently labels the Mac download for Apple Silicon; check compatibility if you have an older Mac.

**Naming note:** Current OpenAI documentation calls this the **ChatGPT desktop app**, with Codex inside it. An older installation or screenshot may use Codex branding. Start from the official guides above because names and buttons can change.

## 2. Sign in

Choose ChatGPT sign-in and use the same account and login method you use for your paid ChatGPT membership. Complete the browser sign-in and return to the desktop app if prompted. An API key is not needed for this membership-based walkthrough. [Desktop setup](https://learn.chatgpt.com/docs/app)

If the app asks you to pay again, check that you signed in to the account holding your subscription before purchasing anything.

## 3. Choose Codex and a local folder

1. In the desktop app's product selector, choose **Codex**. Current documentation describes this as the ChatGPT dropdown.
2. In File Explorer (Windows) or Finder (Mac), create a folder named **Agent Practice** inside Documents.
3. In the app, open that folder as your project or work location. The exact folder-selection label can vary by version.
4. Start **New chat** in that location. If offered a location choice, choose the local computer/folder option.

The official quickstart supports opening a folder and working with its files. [Quickstart](https://learn.chatgpt.com/docs/quickstart)

## 4. If GitHub signup appears

1. Look for wording such as **Cloud**, **Create environment**, **Connect GitHub**, or **Select repositories**.
2. Back out of that setup and return to the desktop app's local folder workflow in Step 3.
3. If connecting GitHub is presented as optional, leave it disconnected for this practice task.
4. If there is no local option, send your coordinator a screenshot of the whole app window and the exact prompt, with personal information hidden. Include whether you use Windows or Mac. That will let us identify the screen instead of guessing which button to press.

The cloud guide explicitly asks users to connect GitHub and choose repositories. This is why a cloud onboarding screen can request GitHub access. [Cloud instructions](https://learn.chatgpt.com/docs/cloud)

**Git and GitHub are different:** a prompt to install Git does not itself mean you must create a GitHub account. Record the exact wording if you encounter it.

## 5. Run a simple practice task

Paste this into your new Codex chat:

> I am new to Codex. In this Agent Practice folder, create a file named START-HERE.md. Put a short welcome message and a three-item checklist in it. Explain where you saved it and how I can open it. Use plain language.

Let Codex finish. Review any permission request and approve only if it matches this practice task. Then open your Agent Practice folder and confirm START-HERE.md exists and contains the requested text.

**Success means:** you signed in, opened a local folder, sent a task, and found the resulting file on your computer.

## 6. Begin your coordinator's actual work

Installation gives you the app; your coordinator's project needs its own materials and instructions.

1. Obtain the project folder/files and starting instructions from your coordinator.
2. Save them in a dedicated folder on your computer. Extract a ZIP first if necessary.
3. Open that project folder in Codex.
4. Paste this starting message:

> This is the project your coordinator gave me. Read its README and AGENTS.md if present. Explain the project's purpose, what is ready to use, and what setup is still needed. Before changing files, explain the first task in plain language.

5. Follow the project's setup instructions. Install extra tools or connect services only when that project needs them.

Your account will need its own access to any shared Drive folders, plugins, or other services used by the project. Installing Codex does not copy your coordinator's computer files, chats, or connected accounts.

## Quick troubleshooting

| What you see | What to do |
| --- | --- |
| GitHub signup or repository selection | Return to the desktop local folder workflow. See Step 4. |
| API key request | Look for ChatGPT sign-in and use your subscribed account. |
| A request to pay again | Verify the signed-in account and its membership first. |
| Usage limit reached | Read the displayed reset or credit options. Plus usage is limited; another installation does not remove the limit. |
| Cannot find the output | Ask Codex for the complete saved file path, then open it in File Explorer or Finder. |
| Screen differs from this guide | Record your operating system, app version, exact message, and a screenshot for your coordinator. |

## 7. Continue your work next time

1. Open the desktop app and return to the same project and chat.
2. Review the last response and any files created there.
3. Give one clear next task, including the file name and desired result.
4. Open the resulting file and check it before sharing it.

At the end of a session, you can ask:

> Save a short SESSION-NOTES.md in this project folder with what we completed, the files changed, anything unfinished, and the next recommended step. Do not include passwords or account credentials.

If starting a fresh chat in the same folder, ask it to read those notes first.

## 8. Tell your coordinator whether setup worked

Copy and fill in:

> Computer: Windows / Mac
> App name and version:
> Signed in with my subscribed account: Yes / No
> Opened Agent Practice: Yes / No
> Created and opened START-HERE.md: Yes / No
> Exact message blocking me, if any:
> Next project I need to open:

Include a screenshot if needed, hiding personal information. Never send passwords, verification codes, or API keys.

## Before distributing a tailored edition

The installation guidance has been checked against official documentation, but this walkthrough has not been tested on the new agent's computer. Capture the operating system and the screen requesting GitHub to make a tailored edition match that installation. Add your coordinator's specific project handoff steps once the intended project is identified.