To redeem your Amazon (US) Gift Card $, please follow the steps below:

Log into your Amazon account.
From the Amazon homepage, scroll over the Account & Lists tab on the upper right-hand corner.
Click on the square that reads, Gift Cards.
In the left-hand column (or just underneath your gift card balance), click on Redeem a Gift Card.
Enter the 14- or 15-digit claim code that came with your Amazon physical card or e-gift card.
Click Apply to your balance, and your balance amount should be updated.
If you havent already redeemed your gift card to your account, you can enter your claim code during checkout. To do it, enter the claim code in the Gift Cards & promotional codes field on the Review your order page. If your order total is more than your gift card balance, well charge the remaining amount to your default payment method. You cant use a gift card to purchase other gift cards 123.