You still need to put in your credit card number in order to place the order. It's not going to bill your card, but you have to put it in. It doesn't take a genius to figure that out.
Watch it here
http://www.youtube.com/watch?v=jSKVI78xYi0
Also, here's a week edit that you should watch too
http://www.youtube.com/watch?v=AptGSvrPYbk&feature=channel