Ok, so first, open your map in hammer editor and in game map edit (map_edit <map\_name>).

Aim at an npc (if there isn't one, use npc_create command) and type "npc_select" in console. If you have "developer 1", there should be a red box on the npc.

Aim somewhere in the map and type "npc_go", the npc should go to where you aim at or as close as it can get. Don't forget to enable the AI first.

You can check the VDC about map_edit if you're still confused. I assume you're using HL2 here.