Get started with Codex.
OpenAI’s agent for working with files, building websites and checking changes in a project.
Install the desktop app
Download the ChatGPT desktop app for your operating system using the official download page.
Sign in and select Codex
Sign in, then choose Codex from the ChatGPT dropdown. Use the official quickstart if your app looks different.
Open a practice folder
Create a folder called waymark-practice on your computer and select it as your project. Use a local task for these lessons.
Check your model and permissions
Choose an available model and review the task’s file and command permissions. Start by asking for a plan.
Try one small task
Use this Waymark practice brief to check that your agent can create a file. Review its plan, let it finish, then open ready.txt yourself.
In this practice folder, propose a plan to create a file called ready.txt containing ‘My Waymark practice folder is ready.’ Wait for my approval, then create it. Do not change other files or use external services. Tell me where to open the file so I can check it.
Use the project folder for local files. Web research depends on the tools and internet access available in your session.
One agent. Plenty to try.
Once you can open your folder and create a file, you’re ready to choose a lesson.
Official setup references
Documentation checked 27 September 2026. App screens, account access and usage limits may change; follow the provider’s current instructions if they differ.