Can't play The Hidden

[PixelDuh]

I tried to install the Source Mod called The Hidden, and I'm having two problems.
Number one, When I first installed it, all of the install files said "skipped"
Number two, when it was done "installing", it said to restart my steam and it would be in my library. It didn't.
I can't play the game at all. If anyone knows how to fix this, please help me.