After downloading the mod, use a program such as 7zip or WinRAR to extract the main folder of the mod.
Drop that folder into the mods folder which is supposed to be in the game's installation folder (don't know where that is? click here)
BeardLib is optional, and is only used for translation to non-English languages and auto-updates.
Color Picker is optional, and is only used for the interface to customize the flashlight color.