How to name an Xbox gamertag:
1. Go to the official website and choose a new gamertag.
2. Log in using the Microsoft account email address and password associated with your Xbox profile.
3. Make sure that the current player code is displayed in the upper right corner of the page after logging in, and confirm that you have logged in to the correct account.
4. Enter the desired new gamertag in the text box and select Check Availability.
5. On the next page, see how your gamertag looks on Xbox services.