After downloading the mod, use a program such as 7zip or WinRAR to extract the main folder of the mod.
Move the main folder of the mod to assets/mod_overrides. The assets folder is supposed to be in your game's installation folder (don't know where that is? click here for PAYDAY2 folder). Create the folder if necessary
which one of the folders do i put into mod overrides? i am putting the soundbanks folder in there and its not working
The main folder you just extracted. Folders such as soundbanks, assets, guis, etc. never go into mod_overrides.