Measure the back of the chair with a tape measure from the top of the chair to the top of the seat. Then measure the width. Cut two rectangles of equal size. Make them two to three inches bigger than your measurements to allow for the seams.
Drape remnant fabric over the chair according to your measurements and pin the pieces together at the seam lines. Cut the extra fabric while leaving a half an inch beyond the seam lines. Measure the seat of the chair and cut another pattern from fabric remnants. Pin the seat cover onto the fabric at the bottom of the chair's back.
Remove the pattern from the back of the chair and mark the seam lines with tailor's chalk.
Cut out the pattern pieces from your cover fabric and sew the pieces together at the seam lines. Sew the right sides of the fabric together and turn it right-side-out to create a smooth seam.
Measure the base of the chair to create the skirt. Cut the fabric for the skirt to the desired length and to the width that you measured.
Pin the right sides of the skirt together and hem the skirt onto the chair cover. Fold the skirt over so it hangs correctly, and stitch down the corner seam to join the edges of the skirt together.
Turn up the very lower edge of the skirt and place a 1/4-inch hem in the bottom.