Which mods Wolfar? Which version of the game do you have and where is it installed on your computer? Steam by default puts the game below it, so it might be in "C:\Program Files (x86) \Steam \SteamApps \common \Wolves of the Pacific", and if such is the case, you would have to move the install to be able to apply mods. Refer to
Moving a Steam Installation and Games, which Steam in their infinite wisdom decided to change the procedure again... let us know how you get along with it.