How do I center this?

[Crystina]

Hello, all. I am fairly new to all of this and trying to trudge my way through. I have come up against a very simple problem, but can't seem to figure it out. Any help would be greatly appreciated.

 

Please go to http://desertroseinspirations.net/catalog/...out_payment.php

 

Username is [email protected]

Password is 123456

 

The entire bottom table is off to the left. Any ideas where I can go to fix that? I just everything centered.