I don't get it

So, I've been trying to figure out how to change just the background on the template.

After much experimenting, I got it!
Or so I thought.

When I get the code into the template and "preview" it, it is there and looks great! When I save it, then go to the blog, all I get is a white background! I don't understand. I have the image saved to photobucket, I'm not trying to link it from some other place. And it shows up right when I preview it...what's up!?!

Maybe it will make more sense tomorrow (instead of now - at nearly 1:00am!)

Any suggestions?