wheres my garrysmod folder?

i cant seem to find my garrys mod folder where you put downloads into.
“what i read what you have to do”

C:\program files\steam\steamapps\username\garrysmod\garrysmod
or
C:\program files (x64)\steam\steamapps\username\garrysmod\garrysmod
or
C:\program files\valve\steam\steamapps\username\garrysmod\garrysmod
or
C:\program files (x64)\valve\steam\steamapps\username\garrysmod\garrysmod

There is also Programs File (x86)

found it but coludnt get them to work

Tried putting them in /addons?