This link will take you to the correct page on SOS to add your gifted membership to your cart: https://www.schoolofsweetgeorgia.com/product-category/memberships/
When you view your cart (click the cart icon in the top right corner), there will be a spot to enter your gift card code just above the square pink SOS logo (you may need to click the pink "Use it here" link to pull up the entry field).
After you've entered your code, click "Apply Gift Card" to update your cart, and it should change to $0.
When you complete your checkout, you'll still be asked to complete the purchase information, but there should be no additional charge.
NOTE: Gift card codes will not work in the "Coupon" field