Simply unrar - then copy the content to your main game folder.
Make sure you have a backup of any previous files.
Original User Interface was created by aysberg and this version only has 2 new options which I added specifically for GSCE.
Number of Qualifying sessions (Tested with version 1.20)
Steering Wheel Range (Found under Rates section) 180 - 900 degrees for wheels that support it.
aysberg's HD Hud for rFactor (GSCE modified)