This is a guide on how to get "The Seventh Column" next to your name on Halo 3 or 2
Halo 3
Halo 2
Step 1: Go to Welcome to Bungie Studios : Satisfy Your Grunty Thirst.
Step 2: Log In using your xbox.com info
Step 3: At the top click on your gamertag
Step 4: Click Edit Profile
Step 5: Go to the Profile Information Tab
Step 6: Scroll to the bottom and set "Customize Halo 2" And "Customize Halo 3" to "Show"