Repating background images - Fluid left and right
 

I want to have an image repeat it the background on the left and right side on a fluid template, from top to bottom. The right image is different than the left. An example of one image would be this:
https://vborg.vbsupport.ru/attachmen...1&d=1272593658

Ive tried this CSS

#leftbg {
background: url(images/gradients/leftbg.png) repeat-Y;
width:215px;
height:2000px; (2000px just to see how it'll look)
float: left; }

I'm not sure where to put <div id=leftbg></div> or if I should even be using div.

Using vbulletin 3.8 with a default skin.

Thanks