I have read that mods should be installed in Steam/steamapps/USERNAME/garrysmod. I haven’t got that folder. I have got a garrysmod content.gcf file in steamapps, but i can’t really install mods.
Launch Garrysmod and it should create the folders upon first launch.
Steam/steamapps/<username>/garrysmod/garrysmod/addons is where they should go when you have performed first launch
Ahh, thank you!