"You can make a gift from the already purchased packages, which are available in the "Donation packages" section. There, at the bottom, you have a "Gift" button, as soon as you press it, you will get an option to choose a player to send the package to.

After choosing the person you are going to give a gift to, click on their avatar picture and you will go to their profile. There you will see the section with gift packs, and on the available offers you will have a blue "Gift" button or an option to buy the offer you want to gift.