To connect Christmas tree lights, first, you'll need to gather all of your light strands and a few extra batteries if you're using battery-operated lights. Then, make sure to lay your lights out on the floor in a neat, straight line. Next, connect the first strand to the plug and the last strand to the controller. You may need to twist the wires together to ensure a secure connection. Then, you can begin to decorate your tree with the lights. Make sure to check all connections as you go to ensure everything is working properly. Have fun!