Prepaid Gold Card

Right now I'm in the middle of a 1 Month Gold Membership. How can I add my prepaid card to the other?

Go to control panel and click on your gamer profile, which needs to go right once, when you see your avatar you in the right place.

Now click on Membership, and you will be a description of your current one click, then add the membership, another popup window, then select redeem code.

go to your Xbox Guide, press the large button in the center, then goo for you the last slide on the left and then press the redeem code and then it tells you what to do