Hello, im making my game. Its a zombie kill game, first person. I have one problem... in the map, there are trees, and i wonder how to do that the zombies dont collide with the trees. Also i want to know how to do the Crouch and Jump actions . Thanks

Take a look at the last AUM magazine for obstacle avoidance (so they don't collide with the trees).

And the Crouch and Jump actions ?

http://tutorial.3dgamestudio.net/

or use IntenseX or any other pathfinder. the simplest to place nodes and make paths in WED