You can make a Christmas tree skirt by cutting a circle out of fabric or felt. Make sure the diameter is larger than your tree's base. Fold the circle in half and cut a slit in the center, leaving enough fabric to overlap at the top. Then, sew or glue the edges of the circle together, leaving an opening at the top. You can add a trim or embellishments to the edge if you'd like. Finally, slip the tree skirt over the base of your tree and adjust it to fit properly. Enjoy your festive tree skirt!