G-Mod download help

umm well i just downloaded G-Mod 10 a week ago and i have downloaded a few add-ons to the game like extra NPCs and ETC. but how do i put them on the game i know it involeves extracting the files but everytime i extract it to where it is supposed to go it says “Path Invalid” so can you guys help? thanks

(sorry im a noob)

It should be extracted to the addons folder inside garrysmod

do you have the original Gmod if not BUY the original its not thet expencive and munch less problems with the original then the one thet is nonsteam!