Each ball has a hole and a cut to push the bulb in easily.
Push with little force the cut to put the bulb into the ball.
Make sure the bulb is inserted securely into the ball! This can be done by pulling the cord, contrary to the insertion direction to lock it with the ring. The ring should remain outside the ball. Pull the electrical cables so that the lamp holds.
String lights is ready when the last ball is put on the chain. Turn on the string light and enjoy the colorful lights!