some real trouble with gmod

OK, so I bought gmod from steam and started playing it.
The first time i saved, and then loaded a save, all of the NPC’s were gone. Same with the doors spawned from tool called ‘‘door Stool’’
SO, basicly, this happens to me every time I load a save. As I sad, I’m a newbie, so the problem could be very easy to fix, I just don’t know it.
Also when I download addon through garrysmod.org And install it (unzipping folder to my C:/steam/steamapps/myusername/garrysmod/garrysmod/addons), nothing works, only way which works for me is SVN Tortoise (turtles :smiley: ) and steam workshop. Can somebody help me to fix it? I can record a video showing this stuff if needed.
Thanks for answers,

Calyptratuss (gmod and facepunch newbie)