Step One is obviously to pick the item/s you want to purchase from the Donation Store , and add them to cart. Please note you need to make sure you're signed in with your Enjin account to make purchases.
Step Two, go to your cart by clicking this button:
and then clicking Checkout:
Step Three is to click Change Account:
and enter the Minecraft username of the person you want to buy the item/s for:
Please make sure you enter their username exactly as it appears in-game.
Step Four, pay for the item/s and your friend should receive their items!