Instructions
Load the "Call of Duty: Black Ops" game disc in your PS3 console and select "Multiplayer" from the main menu.
Choose "Online," select "Player Match," and then select the "Playercard" option from the next menu.
Select "Clan Tag" from the Playercard menu and then choose "Edit Clan Tag."
Select the desired characters for your clan tag from the on-screen keyboard and then press the "Done" button. Your new clan tag will be saved, and it will show up in front of your name in your next match.