To decorate a Christmas tree with mesh, you'll need to start by choosing your mesh. There are different types of mesh available, such as mesh ribbon or mesh garland. Once you've selected your mesh, wrap it around the tree in a criss-cross pattern, starting at the top and working your way down. Secure the mesh to the tree branches using a twist tie or a small piece of wire. Then, add some decorations such as lights, ornaments, or other holiday-themed items. Finally, top it off with a star or an angel to complete the look!