Just contact the seller, he'll give you the country/city info you need......They gottta go pick it up. They also give you an MTCN (or something like that) that you provide to the seller. That way he just strolls into the WU office, gives'em the magic number, and your loot is GONE!
I'd make sure that you know how trustworthy the seller is, 'cause there's no protection if he decides to snarf you.