1. Rename your current Interface and WTF folders to something else; it doesn't matter - it's just so that you can revert to old settings if you don't like the new UI.
2. Download my UI (a zip folder) to your desktop.
3. Open the zip folder and extract both the Interface and WTF folders from within to your World of Warcraft folder.
4. Open your new WTF folder (inside your WoW folder), and rename the folders within. The folder named "YOUR ACCOUNT NAME HERE" should be renamed to your wow account name. Folders named "YOUR SERVER NAME HERE" and "YOUR CHARACTER NAME HERE" should be renamed as well.
5. Run WoW. Certain mods should be in place (like Pitbull4 unit frames, Prat chat box, etc) and certain mods should be out of place (like Bartender4 and Satrina Buff Frames). If nothing is in place, then you probably downloaded the UI incorrectly. The out of place mods need to load profiles named "Vileroze - Magtheridon" in order to appear as mine do.
For bartender4, type "/bar", go to the profiles section, and load "Vileroze - Magtheridon". Do the same for Satrina Buff Frames by typing "/sbf options", DR Tracker with "/drtracker ui", Debuff Filter with "/dfilter", and Gladius with "/gladius ui".
Some people of late have been having some issues with the UI that stem from Windows User Account Control.
If this is your issue, it can be solved by running WoW as administrator.
Shoot me a PM if you are having any troubles, but only after rechecking the Instructions shown in the Spoiler above to make sure you followed them correctly. If you still have a UI issue, a screenshot goes a long way to help me identify the problem.