my new wordpress blog is almost ready

Hi everyone. As I said a while back, I have almost completed the move from blogger to a self-hosted WordPress blog. So far so good, I'm almost done, but if you're curious to know how it is going to look you can check it out at:

http://alansmoneyblog.com

The only thing that I cannot figure out how to do - and maybe one of you can help me - is how to place a banner advertisement at the right hand side of the header. Once I get that up and running it will be perfect - and I'm a big perfectionist.