Step 5: Connect the transistor

Picture of connect the transistor
Now you will need to connect your transistor to your Arduino and to your device. Look at the picture below for how to wire it up. I have annotated it if you need help. That little black thing is your device.   If you know the polarity of the wires you can connect the positive to the left terminal of the transmitter and the ground to the right terminal 

If you  want to control more buttons connect additional transistor's the same way but instead of using pin 12 use 8, 9 or 11