Instructions
Select your Gamertag avatar from the "My Xbox" menu. Click "Customize Avatar," "Gamer Picture."
Press "X" to choose a pose from the "Advance Mode" menu or select one of the pre-installed options.
Scroll to the bottom right, and select the background color you want for your GamerTag. You can choose from colors such as violet, red and more. Press the "A" button to confirm your selections and color your GamerTag.