Have you patched you system for allowing custom themes? if not you will have to do that
I would use Universal Theme Patcher, it works great and it's free too use.
If you are running a 64-bit operating system, you need too patch your system 2 times, one time for 32-bit and one time for 64-bit, you need too patch 5 files in total.
This theme also requires you to have Theme Resource Changer installed and running.
But if you dont have this, you can read more about TRC here: [link]
Too add the theme, you just need to unzip the pack, and add the Re-degetized folder and the Re.degetized.theme file too: C:WindowsResourcesThemes
Then you can go too your desktop and right-click and choose Personalize and you will find it with the other themes you have installed in your OS.