Hi CaptKill4Fun and @WebbedShrimp1
You change the picture and gamertag through XBOX. MS allows you to change a gamertag once for free, after that there is a fee.
You can do this with the XBOX app or can log into XBOX online.
https://support.xbox.com/en-US/help/account-profile/profile/change-gamerpic-on-xbox-one