it is very easy
1) pick your stuff in the shipping cart
2) fill in the shipping address, which is your friend address in US
3) fill in the billing address and your credit information
4) they will give an order summary before your confirmation
you are done
while i think that is the process. maybe it is backward. but i think you have no problem at all. At Amazon.com or Amazon.ca, you can refund anything you are not satisfied.
While, this is my experience.