Turn on your bike and then hold the "+" button for a few seconds. To turn them off, hold the "+" button for 3 seconds.
The lights should turn on and off. If they do not, you may have to swap the location of the positive and negative wire at the light.
In a rare case, if that does not resolve it, reach out to Support@Ride1UP.com with a few pictures. Let us know what you tried so far and any related information. We will work with you to make sure they are working!