how to put lights on a christmas tree vertically

That's a tricky one, but there are a few things you can do to make it easier. First, use a small, lightweight light set, like the mini lights. Then, start at the top of the tree and work your way down, wrapping the lights around each branch as you go. Be sure to keep the wires as close to the trunk as possible, and try not to overlap too much. With a little patience and some careful wrapping, you should be able to get a beautiful, evenly lit tree!