These are themes for the Blackbox window manager. Assuming you have Blackbox installed, all you have to do to install these is move the .tar.gz file to ~/.blackbox and uncompress them. If you don't already, you should have the following directories under your home directory:~/.blackbox
~/.blackbox/Backgrounds/While you're at it, go ahead and create a symbolic link from ~/.blackbox/Backgrounds/ to ~/.blackbox/backgrounds. You can do this by typing "ln -sf Backgrounds backgrounds" in the .blackbox directory.
Though the background files are supposed to live in ~/.blackbox/Backgrounds, many theme authors use the lowercase version when writing their themes. Setting up a link is the easiest way to adjust for this. (Thanks to James Bussard for pointing out a blatant typo in these instructions, which, if followed, would have rendered all these things unusable.)
I have found bbconf to be a great tool for blackbox configuration. Like wmakerconf, it also functions as a theme configurator and has a snertly GUI.
Themes contributed by Marek Fetlinski