The safest way to patch your system is with UxStyle Core. UxStyle is a bit of software that relaxes Windows theme signature requirements to enable third-party customization. Specifically, UxStyle consists of a tiny system service and a kernel driver that are loaded into memory where they hang out until reboot. No file system changes are made.
*Visit this page and download the version that supports your OS version: Website
*Unzip the program and install it as you would normally install a program on windows. That's all you have to do. Custom themes can now be used on your system.