iTunes gift certificate code

In iTunes, go to the store....Click on your account name and the pull down window that appears, you will see, "Redeem" click on that and it will have you enter the code.

read these instructions: http://support.apple.com/kb/ht1574

TThanks dear

there are two different ways to redeem iTunes, depends if this is your first time as for creating US account then you can add gift code instead of credit card during registration as well ....