You need lots of time to practice.

Wel, you could start with looking at some tutorials. There is a tutorial for how to model, compile and skin a knife. I'll add a link later =)

Edit: Link

Did you look through the tuts in the cs:s section? also, you need modeling programs like milk shape 3d or 3ds max. not only that but you'll need a LOT of patience and practice to get good. this is where most people get stuck because they don't have the patience to take time and learn how to get good before releasing things. read tutorials and stick with it and you'll get good if you work at it. :D

It's easy, it's basically the same as source. just play around with the .qc, you'll understand it in no time.