i think you should get a repair manual and read it , no one is going to type a how too on using a timing gun , but ill give you a taste, connect the two wires from the timing gun where the suspsed to go , spark plug wire, battery, point the gun at the crank shaft, youll see a line, move the distributor until the line is at tdc mark , but the manual will describe in detail , and if you dont see a line when point the gun at the crank , you got a tooth issue.