Help needed for "floating" image

On my three StoreFront pages I've added B&H ads. On my longest page http://donwiss.com/pictures/BrooklynStores/ you can see a single B&H ad at the top of the right table column. The page is long. I'd like that ad to remain in view as the people scroll down.

I found a page doing what I want. I looked at the source code. It is beyond me to understand it. Based on the image size it is in this code:

<div id="bnslsp3" style="height: 600px; width: 160px; display: block;
padding-left: 3px;">
<!-- BEGIN RAW TAG - 160 x 600 - ROS: Run-of-site - DO NOT MODIFY -->
<IFRAME name="bnr3" id="bnr3" style="position: absolute; z-index: 10;"
FRAMEBORDER=0 MARGINWIDTH=0 MARGINHEIGHT=0 SCROLLING=NO WIDTH=160
HEIGHT=614 SRC="http://www.xxxxxx.com/cached/cpxr_pab.php"></IFRAME>
<!-- END TAG cpxr. -->
</div><script language="JavaScript" type="text/javascript">
<!-- start opera fix
if(navigator.userAgent.indexOf("Opera")!=-1){

setTimeout('Scrollinit();',1500);
}
// -->
</script></td></tr></table></div>

[end of code excerpt]

How would I adapt that to my needs?