Miss Addons folder In gmod

I am currently playing gmod and i notice every one has flying errors everywhere and i i have download everything from garrys mod website just to get rid of them the problem is my garrys mod folder doesn’t have a Addons folder and all my friends say i should and i even made up my own addons folder and i wa wondering can some one help me fix this problem because when i put my shit in there it still doesn’t work :C

Create that folder, if you don’t have any source game and BOUGHT SOMEHOW gmod, you won’t play.

Make it yourself

I did try re installing it from steam and every thing would i work if i put i tin the downloads folder?