The first step is to unplug the tree from the power source and remove any ornaments or decorations that may be on it. Next, you will need to loosen the strings of lights that are already on the tree by turning the screws at the base of each string. Once the lights are loosened, you can start removing them one by one and replacing them with new strings of lights. Make sure to carefully wrap the new strings around the tree branches and secure them in place with clips or wire. Finally, plug the tree back in and enjoy your newly re-lit Christmas tree!