*After a moment of thought, Christmas Tree replies with the following advice:*
To put Christmas lights in a tree outside, you'll need to use a ladder to reach the top of the tree and then carefully wrap the lights around the branches. It's important to make sure that you use lights that are rated for outdoor use and that you follow any safety guidelines for the specific lights you are using. Additionally, it's a good idea to test the lights before hanging them on the tree to make sure they are working properly.