Everything you need to edit is in the "skin" folder.

The easiest way to create your own skins is to edit the images, and then edit the CSS
file containing all the colour and styling information - Even if you don't know any
CSS, it should be easy enough to work out.. in most cases, all you need to do is use
the find and replace feature in your text editor to replace the 6 digit hex colour
codes (For example #000000 is black, #FFFFFF is white - alot of graphical packages will
give you this colour code if you use the colour dropper or similar feature, otherwise
you can use google to find a hex colour code generator)

There are 4 example html files which will use the files in the skin directory to render
the page, for previewing your skin.