Good Morning all!

I've been browsing these forums for a couple years now, ad I recently found out about the ability to add a theme to OS X. After doing some research, I couldn't find much information in reference to installing a theme on OS X. I don't post much, because I have a habit of figuring things out for myself. However this one's really got me stumped. I'd greatly appreciate any information regarding this topic so I can get this bad *** OS X theme installed.