Look at my first reply to this thread. You have to create a background image to do the shading.

Right, I did exactly like you said in the first reply to get the background I have currently. But if you look at the site I linked you will see that the background is black, but they have still managed to shade the sides of the center column. I was just wondering how they did this.

What you want to accomplish is a bit complex to explain. The best way to figure out what is going on with another site is to use Firefox with the firebug extension and look at the source code. You should also check out the "Showing Off" forum for Atahualpa examples of what you are trying to accomplish. I wish I could give you a simple answer.