PSA: I can't get almost any game to run for me in fullscreen mode with ReShade. I must set the game to borderless-window before installing ReShade on a game.
To Install Any ReShade Using the 3.0 Framework or Above, Do this:
1) Go here: https://reshade.me/
2) Download the latest version (3.0.7 currently) and select the "dirt4.exe" in your root game folder.
If downloaded through Steam's default directory it's usually this: "C:\Program Files (x86)\Steam\SteamApps\common\DiRT 4"
Select the "directX 10+" version when it asks. Say yes to all when it ask if you want to download a collection of shaders and effects.
3) Run the game. Press shift+f2 to open the ReShade menu after all the effects finish loading (big message at the top of your screen) and follow the on-screen instructions till the boxes aren't red anymore. Close the game.
4) Go to the preset you want to use and download it. Rename the file you download to "anythingyouwant.ini" from ".txt". Put the file in your game folder. Run your game. Select the new preset from the ReShade drop-down menu once the reshade effects finish loading. Profit.