To wrap Christmas lights in a tree, start at the bottom of the tree and wrap the lights around the trunk. Wrap the lights in a zigzag pattern, working your way up the tree. Make sure to leave some space between each strand of lights so that the tree is not overpowered by the lights. Once you reach the top of the tree, secure the lights with hooks or clips. You can also use ribbon or garland to hide the wires if you want a more finished look.