Hmm... I'll try that. Yeah, I am using Steam, so that may well be the problem, in addition to that, I was trying to make a CS map... Maybe I should try just HL first? I'll work with it, and come back if I need more help...
[EDIT] -- Okay, so yeah, that worked perfect, thanks! Apparently it compiles and everything perfectly, but Hammer itself can't launch my CS directly.
When I go into the game, I can actually start a server and select my map from the list and play it.