STALKER Mod Thread

I've been kicking around the idea of creating a mod for STALKER: Call of Pripyat.

I really love the zombified stalkers and I wanted to create a new independent area where the player defends a building against waves of zombified stalkers. Eventually work it out such that there's a day/night cycle and have the waves come out at night.

Now, I have never made a mod before so I'm kind of at a loss as to where to start. Any suggestions?

First do you do anything- program, model, draw?
2 you need to keep your ideas in mind, and KEEP THEM REALISTIC, that is the failure of almost all indie games in dev
3 I would suggest you join someone, work with them, publish a game and then work on the game so you have a better understanding of the gaming universe

My skills in those areas are, sadly, non-existent. I was hoping to use models already in use in the game.

I'm trying to figure out if its reasonable to develop a mod for the game, not an entire game in and of itself.

can any one tell me installation of secret trails 2 im unable to run the game it get crash on starting