Trigger Remote WIth Arduino

I have a car key fob with buttons for locking/unlocking the car. I was wondering what the best way to simulate the momentary switches being pressed using an arduino. I have a couple of NPN and PNP resistors but I am not sure how to wire everything up. I have a wire soldered to the trace (red) that is connected to the IC pin and another soldered to the ground (blue). When I touch the wires together it works. I tried connecting the red to the collector of the transistor and the blue to the emitter and then sending a HIGH signal from a pin on the arduino to the base but that doesn’t work.