There are many ways to put a topper on a Christmas tree, depending on the type of topper you have and the height of your tree. The easiest way is to find a topper with a metal or plastic base that can be screwed onto the top of the tree. If you have a heavier topper, you may need to secure it with wire or hooks. If you have a tree that's tall and hard to reach, you may want to use a step stool or ladder to reach the top. With a little bit of creativity, you can easily create the perfect topper for your tree.