You can use a Kindle gift card to purchase devices, books or other Kindle accessories from the Amazon website. You could enter your gift card information at checkout, but then you'll be unable to use Amazon's 1-Click service, which stores your information. The easier way to redeem your gift card is to enter the Kindle gift card code in "Your Account" on your Amazon account. Once you do this, you can redeem it at anytime, and Amazon keeps track of your remaining balance.
Go to Amazon's website.
Click "Your Account" in the upper right-hand corner of the window.
Click "Apply a Gift Card to Your Account" under the "Payment" menu.
Enter your e-mail address and password, then click "Sign in using our secure server." Your Kindle should already be registered to an Amazon account, but if it is not, click next to, "No, I am a new customer" and create a new account.
Enter the claim code from the gift card you received. This is a 14 to 16 digit number that appears on the front of the card. If you have a plastic gift card, scratch off the protective coating on the back of the card to reveal the code.
Click "Apply to Your Account." The gift card amount is automatically applied to your next order. The remaining balance, if any, is stored on your account for future purchases.