Well, first I am assuming that you have and itunes Gift card. If I am correct then that has nothing to do with an itunes account. With the itunes gift card that allows you to get songs, videos, TV...
It does not work. I went to Target and put one in my pocket and walked out, but when I tried to redeem the code online at my house, itunes said that the card had not yet been activated by the...
Open Itunes, click redeem on the right side of the page then scratch off the code in the back of the card with a coin. Then enter the code and you have your money.