Ho ho ho! That's a great question. Hanging Christmas lights in a tree outside can be a bit tricky, but with a little bit of planning and patience, it can be done. The first step is to make sure you have the right type of lights for your tree. Outdoor lights are typically designed to withstand the elements and won't be damaged by rain or snow. Next, you'll need to make sure you have enough lights to cover the entire tree. Once you have your lights, you can begin by securing one end of the light strand to the top of the tree using a tie or hook.