how can i make a storm trooper npc walk in single player or multiplayer?
please tell me what script i should use or how i should make the script
and how to apply it

Since I'm not at home I can't give you specific instructions. However you get the SP and MP scripts. with the editing tools, so you can check one which has a name like patrol2point or something.

Basically you have to place some waypoint_navgoals with targetnames then in the script set the navgoals for the NPCs. There is a set command for this with a very similar name. If you set a navgoal for the NPCs they will walk to it.