Create a practice folder
In File Explorer on Windows or Finder on a Mac, create an empty folder called My first Codex project in a location you can find. An empty folder makes the output easy to identify.
Open it in Codex
Choose Codex in the top-left app menu. Create a local project and select your practice folder. A folder is enough for this exercise; a Git repository is not a prerequisite. A repository is a project with tracked versions of its files.
Give it the build brief
Paste the prompt below and send it. If the app asks for permission, read the action and the path before deciding. OpenAI recommends Ask for approval for most work. You do not need Full access for this exercise.
Open the result
Ask Codex to open the HTML preview or tell you exactly where index.html was saved. You can open that file in a browser yourself. HTML is a file format for a web page. Local means you are opening it on your computer; it has not been published to a website.
Test one behaviour
Tick an item, untick it, then try the reset button. Ask Codex to fix anything that fails. For the next change, try: Show how many items are complete, such as 2 of 4. You now have a concrete reason to review a second version.
In this practice folder, create a single index.html file for a workshop checklist. Include four items: confirm venue, send invitations, print name tags, and test projector. Each item needs a checkbox. Add a Reset checklist button. Use readable text and make it work on a phone. Keep it self-contained, with no external packages or services. Do not publish it. Open a preview, check the checkbox and reset behaviour, and tell me the saved file path and what you tested.
Sources and availability
Checked 6 September 2026. Labels and access can vary by app version, account, and workspace. Practice examples are created for this guide.
OpenAI: Desktop quickstart OpenAI: Permissions OpenAI: Work with files