You will first need to open an Amazon.com account and redeem your gift card. Once you do so, the gift card amount will be applied to your Amazon account. You can then use this account balance to pay for any purchases you make on the Amazon website. You have to make sure that you use the correct gift card on the respective website. Amazon has different websites for the United States, Canada, UK, Australia and others. So you have to make sure you are using the right gift card on the respective Amazon website. If not, it won’t work and you will not be able to use it. Please note that you may still be required to enter your credit card or bank account details at the time of checkout even though you are using your gift card balance to make the payment. Amazon will not charge your credit card or bank account if your payment doesn’t exceed the balance in your gift card account balance.