Eh..hm.. I don't quite remember how to set up the game configurations, but I believe
this should help you out there. I used to play with hammer alot, and I like to think that I got quite good with it ^-^
Dunno why you had such a hard time stariting it up though o.o
Edit:

I'm having the same start up problem too! I just didn't realize because I haven't attempted to use SDK in many months o.o
Anyways, that website I sent you will only help you set up the configuration for gmod9, which is pretty much pointless unless you plan on working with a game mode, try looking around on the
valve wiki, there should be something there.