The aim is to replace 3 system files with the patched ones you downloaded. There are a few
programs that do it automatically, but I'll explain how to do it manually.
1. Navigate to your Windows/system32 folder
2. Find uxtheme.dll
3. Right-click and select properties.
4. Goto Security and click Advanced.
5. Goto Owner and click Edit.
6. Select your username from the list and click OK, then OK on the popup.
7. Goto Permissions and click Change Permissions
8. select your username from the list and click Edit
9. Tick the 'Full Control' box and click OK (4 times to get back to folder)
10. Now rename uxtheme.dll to uxtheme.dll
.bak
11. Copy the patched uxtheme.dll to the system32 folder.
11. Repeat steps 2 thru 11 for both themeui.dll and themeservice.dll
12. Reboot and you're done.
Now it's just a case of installing the theme. Themes are kept in the Windows/Resources/Themes folder. You'll see a few .theme files there and a sub directory called Aero. This sub directory also contains the Basic theme files.
The file you need to replace is inside the aero folder, called aero.msstyles. Rename it aero.msstyles.bak, then copy the downloaded file in to replace. You then just need to log out and log back in again.
Tbh, the writer of the themes I linked to has been a bit lasy. The standard practice is to make an entirely new theme folder that you can switch to in the display properties dialog box, but instead he expects you to actually replace the default theme. Because of this, I recommended you rename the file first and keep it as a backup so you can switch back in the future.