To hang Christmas lights on a ceiling, you will need the following materials: Christmas lights, extension cord, ladder, and tape or hooks. First, find the center of the ceiling and mark it with a piece of tape. Then, string the lights from the center out to the edges of the ceiling. Make sure to leave enough slack in the lights so they don't pull too tightly on the center. Next, plug the extension cord into an outlet and use tape or hooks to secure the lights in place. Hang the lights as evenly as possible for a beautiful display.