I am sure you have already registered you Nook through Barnes and Noble. If not you need to create an account with them. This will require a valid credit card. After you have registered/created an account, you can add your gift card at Barnes and Noble. Sign in, go to MY ACCOUNT, then scroll down to GIFT CARDS AND CERTIFICATES, click MANAGE GIFT CARDS, then add your card. As long as you have credit with a gift card, your credit card won't be charged for any purchases.
If you have any questions, you can call the 800# at Barnes and Noble..they were very nice and helpful for me! Good luck and happy reading!! LOVE MY NOOK!

You have to go to your Barnes and Nobel account. Actually, I find is SOOO much easier to do that on my lap top, then everything transfers to the reader automatically! Good Luck!

You have to set up an account on Barnes and Noble's website. Then you can add the gift card on your account page. However you must list a major credit card when setting up the account. Hope this helps!

You can access your payment info with the setting button and the bottom right of the screen, then click shop! It allows you to manage your credit cards through there! If not there then try logging into your Barnes n noble account like u were buying a book and c if u can set it up on there site! Other then those two ways idk! Good luck!