Instructions
Sign into your Bungie.net account. The "Sign In" button is located on the upper right corner of the Bungie homepage.
Click on your name to display your profile information. Proceed to the "Game Settings" tab and then "Nameplates."
Select a Nameplate for your Gamertag in "Halo Reach." Find a nametag that you like and press the blue "Change Nameplate" button to have it applied to your profile. You will notice the change the next time you play "Halo Reach" on Xbox Live.
Read and complete the prerequisite to use the Nametag if Bungie.net doesn't instantly allow you to apply the Nameplate to your profile. For example, you must have played "Halo 3: ODST" while signed into Xbox Live on your profile before you can use the "ODST" nametag.