Adding game Contents as addon, HELP

after purchasing gmod i was hoping it would work with my half life 2 ultimate edition (legit, its what they had before Valve complete pack) but unfortunately it doesn’t support it. I tried the method from gmod wiki (http://wiki.garrysmod.com/?title=Adding_Gamecontents_as_Addons) but had no success. Could someone better guide me through this tutorial and is there a way to do it all at once instead of individual folders for each game?