You can't use your bank account until it's verified, I believe. That involves them making two small deposits to your account and you telling them what the amount is.
I'll also mention that unless you have a credit card attached as well, they'll treat everything like an e-check. That means it will take one to two weeks for any payment transactions to take place; your bank has to pay and the entire thing has to clear on the other end before they'll consider it done.
They do the same thing if your credit card expires....
Lesson learned.