You need to follow this guide. To setskin, just use SetPlayerSkin(playerid, skinid) under OnNPCSpawn.
EDIT: If you want a static NPC, just simply go into a server (preferably your own) and go to the spot where you want the NPC to stand. Then make sure you have the FS loaded and type /ofrecord and without moving at all, type /stoprecord. Before you create it, make sure you type /interior (If you are inside) and remember that number. Then go back to your OnNPCSpawn and add SetPlayerInterior(playerid, *NumberHere*)