selector { background: url('images/mules.png') center top; }

Shown to the left are image backgrounds for the body.custom, #header, .menu, and #footer.

The herd did not repeat these images. For gradients, fades, tiles, and other -- typically seamless -- images, repetition can be useful.

A background image can be assigned to any DIV id or class through use of CSS and a valid file location (URL). Where you will fail, human, is in the part about valid and URL.

If you have an image named "mules.png" -- then, as a Thesis user, the herd recommends you use FTP or your host's Control Panel (CP) to upload the image to /custom/images/mules.png -- if you do this, you can reduce the file path reference. Example: images/mules.png -- a relative URL.

If the relative URL fails... or if you have chosen another location... then an absolute URL can assist. Example: http://doublemule.com/pics/mules.png -- calf simple! But you're going to blow it... of this we're sure.