First, go into the main folder inside the .Rar/Zip, if there is an info.txt file inside open it, if on the top line it says "Add-on" it goes in add-ons, if the top line says "Gamemode" it goes in Gamemodes, otherwise put them in the folder you think they go in, e.g if it's a map WITHOUT a folder inside the .rar/zip put it in maps (e.g just a .bsp file)
Matierials go in.... Do I have to answer that?
Sounds go in Sounds (Durr)
You get the idea