You've decided to use your Amazon Gift card. That's great, you've earned it!
This is what you'll need to do:
1. Go to www.amazon.com and click on Gift Cards & Registry and select Redeem a Gift Card.
2. Sign in to your Amazon Account.
3. Type in your claim code (see: How Amazon Gift Card Looks Like and How to Get It?).
4 .You're required to redeem your gift card code within a year. Once redeemed, the entire gift card amount will be stored in your account's gift card balance, which doesn't expire.