Hi Energy - you need to edit the background image slices as well as teh CSS - using photoshop, fireworks, or the free Gimp, etc - they tile vertically:
blackbearpro15.joomlabear.com/templates/...rpro/
images/body.png
blackbearpro15.joomlabear.com/templates/...images/
body-left.png
etc
so you would want to move teh grey line accross by how ever many pixels you are editing the CSS by.
Additionally there is CSS in the index.php for this template - look near the top for the conditional php and CSS blocks - the CSS varies depending how many columns you are using.