If its a Buds gift card, you will have to select the Credit Card option to use it. Unfortunately, you don't get the "cash price" with a Buds gift card as I found out when I tried to use one. If you are using a VISA, MC or AMEX gift card you have also have to select the credit card option.

When you get to the "payment information" page on checkout, you will see a note at the top under "payment method" which states, "(You can enter Gift Card Codes on Next Page)." That is the "confirmation" page which is where the gift card code you received is entered.

When you go to make a payment, near the bottom there is a place for gift cards and it's near promo codes. Also, you can pay for layaway with gift cards or buy gift cards with prepaid Visa cards, which is great.

In the payment screen there is a line to enter a gift card code. You plug it in there and it will apply the gift card.