Gifting allows you to purchase an item, or items, available at GOG.com for your friend. To use the gifting option, first proceed like you would with any other purchase, and go to checkout. Make sure to check the "gift this order" option, on the right side of the checkout page. This order just became a gift order and, after you input the recipient's e-mail address and pay for the order, a gift e-mail will be sent to the gift recipient.
There are some restrictions for purchasing gifts on new accounts, depending on the payment method used.