I know how to download things from, but how can I get them on the game?

It depends on what your downloading. Most of the time you would be downloading files that belong in the garrysmod/addons folder. Drag the file you downloaded into this directory. C:/Program Files/Steam/steamapps/garrysmod/garrysmod/addons. This won’t work all the time, since not all of the files uploaded to are addons, but most of the files uploaded there are addons. Also try looking in the zip file and see if there are instructions on how to download and where to put it. Most of the time people will put a readme.txt, or installation.txt file, just to help people that don’t know where to put the file(s). Example: Such as if it is an adv dup file, you wouldn’t put it in addons. It would go in garrysmod/data/Adv Duplicator. Hope this helped you.

Where do I find the C:?

Have you ever used a computer before? It’s the main directory of your computer. That’s indicating your Hard Drive.

I guess I got to do it by myself…Without any help.

People were helping you, you just don’t know anything about computers, to dumb it down though, the c: drive is usually where you go to find your “program files” folder and the like.

Boy do I hope schools back in sometime soon.