Looks like you may have skipped the first step of the readme file...
Step 1 - Admin CP Modifications
Go to your Style Manager under 'Styles & Templates' in your Admin CP.
Choose to modify All Style Options.
On this page, you will see a section for "Image Paths". Here you must change the path for each image directory (Title Image, Button Images Folder, Miscellaneous Images Folder, etc) to the full path (ex - /forum/images or
http://yoursite.com/forum/images).
You must do this for each of your styles, otherwise your images will not show up!