If you want to change Labra’s background, the basic changes necessary are explained here:
http://www.joomlart.com/forums/topic/adding-a-background-image-in-ja-labra/
BUT–you will also need to change the colors in quite a few template (and tab) images for all the rounded corners. The relevant files are scattered across several different directories and there is not a complete master PSD file for the template. Even with Firebug or CSSViewer, recoloring is a challenging process of finding out what goes where.
ALSO–unless you disable all resizing and drag-and-drop functionality to make Labra a fully non-fluid, fixed-width template, you cannot add a multicolor background image without causing problems with the rounded corners because they will block out the background image. This is because the rounded corner images have their transparency set to the inside area rather than outside the corner, which is your base/body background color. This is necessary so the corner images cover up the background color of the containing div.
I don’t see a simple solution to any of this. It would probably require a major rewrite of the template and tab CSS as well as a recoloring and changing of transparencies in the corner images.
The space between the tabs is another problem:
http://www.joomlart.com/forums/topic/changing-background-between-tabs/
Am I missing something? Has anyone worked out a solution?