The account name of the Steam platform is filled in when registering. The steps are as follows:

1. Visit the official website of the Steam platform.

2. Click the "Register" button on the page.

3. Fill in relevant information on the registration page, including account name, password, email address, etc.

4. Read and agree to the user agreement and privacy policy of the Steam platform.

5. Click the "Register" button to complete the registration.