To create a standard Christmas tree skirt, you'll need about four yards of your fabric of choice.
Cut the largest circle you can to create the skirt, but try to keep the diameter smaller than the widest part of your tree’s branches. If the fabric you purchased isn’t wide enough, either safety pin (from the underside, so the pins are practically hidden), fabric glue, or sew two pieces of fabric together side by side to create a wider swath to cut from.
Cut a long slit from the outside edge to the center of the circle. Then, cut out an inner circle where the tree trunk will fit inside. For even looking circles, use a pen to freehand draw the shapes before you cut them out.