If you're looking to hang Christmas tree lights vertically, there are a few steps you can follow to achieve the best results. First, determine the height and width of your tree, and measure the length of the lights you want to use. Next, use zip ties or hooks to attach the lights to the top of the tree, making sure to spread them out evenly. Then, work your way down the tree, attaching the lights to each branch in a zig-zag pattern. Finally, connect the lights to a power source and test them to make sure they're working properly.