Background image & form in only 1 cell of a header extra widget cell?

Boy, that subject line was a mouthful!

Okay, here is the website in question:

www.bestbiztips.com/susankmorrow

What I want to do is place a form on the right side of the header (as you can see from my words "Promo box for free gift....").

I was thinking of adding a widget with 2 cells - with the form in the right hand cell. But then I would need to put the image as the background in that cell with the form coded into the cell.

Is this the best way to accomplish what I want? If so, how do I define a background image for 1 cell in the header widget?

Oh and if properly I hand code the form into the cell, will the form work?

If you think/know there is a better, easier and more stable way to accomplish this, please let me know!

Thanks as always for all of your help!

KIP