Can anyone tell me how to get their gamertag to appear when you post a quote.

I havent gotten Modern Wafare 2 yet but I know all the weapons and I wanted to know if the M21 EBR is a good sniper. By the way I'm getting MW2 for Thanksgiving or Christmas. P.S: My Xbox 360 gamertag is M21 Firepower and I just created my account but I am a good sniper so pleaze add me to your friends list. I only have silver by the way.