Open the wishlist link the owner sent you, find the wish you want to give, and use its Buy link to go to the store and buy it there. Wishpicks doesn't sell the item — it sends you to the external store, where you pay and arrange delivery directly.
Reserve the wish first, so no one else buys the same thing.
Steps
Open the wishlist link. You don't need an account to view it.
Find the wish you'd like to give.
Click Reserve on that wish and confirm. This marks it as taken so a second person can't reserve the same item.
Click the wish's Buy link to open the store.
Buy the item in the store, paying and choosing delivery there as you normally would.
The Buy link only hands you off to the external shop the owner saved, and Wishpicks never handles the payment — see "Does Wishpicks process payments?" for the full picture. In some regions the first click also brings up a one-time card ("You're almost at [store]") asking whether to allow affiliate links. Either choice — Allow and continue or Continue without — reaches the same store at the same price.
What to expect
Reserving is not buying. Reserving only marks your intent so others don't double-buy; it doesn't place an order. See "How do I reserve a gift before buying?"
One item, one reservation. If a wish is already reserved, someone else has it — pick a different wish.
The surprise is safe. By default the owner doesn't even see that an item was reserved, and your name stays hidden. See "Can I see who reserved or bought a gift?" in Gift Reservation.
Wishpicks has no delivery-address feature — there's no address on a wish, wishlist, or profile. You buy at the store and arrange delivery directly with the recipient, or they share their details with you privately. See "How will someone know where to send my gift?"