How to display background images from CSS included by modules
Basically given:

background: url('images/stadium.jpg') no-repeat left top;


The image will be loaded from the path relative to the CSS file.

e.g:

/styles.css
/images/stadium.jpg


The image is loaded from the relative 'images' subfolder.

Presumably, if the design is all controlled by a module, you could drupal_add_css the css file and have the image files relative to that in the module folder.