Questions after installation - Tabs & Paths

[CompuBlog]

Hmmm, perhaps I should have worded that differently. I'm trying to figure out which file to edit for the previously described background, so that any and all available themes have the same background. That would be a global background image that shows up everywhere outside of the header/body/footer constraints.

Changing the background in the css.php file within admin/template/ only works for the admin section.