You must download minecraft forge at http://files.minecraftforge.net/. Second, you follow your version and install it!.
3. Download the Mod
4. Drop the entire mod zipped file into your mods folder (Search %appdata% on your PC then go into .minecraft, then mods(create this folder if it is not there))
5. Open Minecraft and make sure your profile is set to Forge
6. Play! P.s: You can download mods here!:http://popularmmos.com/minecraftmods/ If you still stucking, tell me!