Image 1 - gm_devworld mod for Garry's Mod

-Extract the .ZIP file wherever, and place the .BSP file into: C:\Program Files (x86)\Steam\steamapps\common\GarrysMod\garrysmod\maps -Go into the sound\custom folder and drag all into: C:\Program Files (x86)\Steam\steamapps\common\GarrysMod\sourceengine\sound -And finally (we're almost there don't give up on me yet!) go into the materials folder and drag the custom folder into: C:\Program Files (x86)\Steam\steamapps\common\GarrysMod\garrysmod\materials