Repeating image behind comments., HELP! Options

[ZeT0]

Alright, so my layout backgrounds always end up being over 1 mb, so I have to save them as lower quality to still be able to upload them to image shack.
So, what I would like to do, if finish it half way, and just make the bar where the comments are, repeat.
A perfect example is this myspace ;
http://www.myspace.com/forthefallendreams
The background stops about half way, and you can see in the comments its just the same image repeated over and over.
That's exactly what I wish to achieve.
Can anyone help!
Thanks.

EDIT:
Just found the code :

CODE

.tablebg { position: absolute; top: 1850px; left: 50%; height: 11500px; width: 979px; overflow: visible; background-color: transparent; background-image:url(http://www.phillm.com/temp/forthefallendreams/tbl_bg.jpg); background-position:top center; background-repeat:repeat-y; margin-left: -493px; z-index:-9;}

Although i'd still like if someone elaborated on it a bit more so. :)