On a one button remote, hold the button down while looking at the red square on the edge of the key fob. If the battery is good, this square will blink.

To sync the remote to the car, press the remote button twice while aiming it at the car then insert the key in the ignition and turn it to run.

Remember, the remote on these cars is a infra red light beam like a TV remote. You can also aim it into a video camera and look for flashing. Test your camera with a TV remote as some cameras are not IR sensitive.