1. Open your World of Warcraft folder.
2. Backup and then delete your 'Interface' and 'WTF' folders.
3. Download 'cr33xUI'.
4. The RAR-File contains two folders: 'Interface' and 'WTF'. Extract it to your desktop and copy these two folders into your World of Warcraft folder.
5. Rename following folders:
X:\World of Warcraft\WTF\Account\ACCOUNTNAME -> Your account name
X:\World of Warcraft\WTF\Account\ACCOUNTNAME\SERVERNAME -> Your server name
X:\World of Warcraft\WTF\Account\ACCOUNTNAME\CHARACTERNAME -> Your character name
6. Start World of Warcraft and login into your Account.
7. Make sure all Addons are enabled (check 'Load out of date AddOns').
8. Enter the World.
9. Go to your graphics options and set the resolution to '1920x1080'.
10. On the left side choose 'Advanced' and activate 'UI Scale' (set to '1.0).
11. Type '/reflux switch cr33xUI' in your chat.
12. Open up the X-Perl options interface with '/xperl' and choose 'cr33xUI' as your profile.
The options for all other AddOns can be accessed by pressing ESC -> Interface -> AddOns.