Measure and cut the tulle so it's 3 1/2 yards long.
Wrap a 3 1/2-yard length of tulle at the base of the folding chair back from the front -- or seat side -- to the back.
Tie the tulle into a tight knot at the center-back of the folding chair. The tulle width will scrunch down to about 10 inches, creating a shirred effect.
Tie the tulle ends into a bow. Pull the ends down to minimize the bow loop, or pull on the loops to enlarge the bow and shorten the ends.
Fluff the bow loops out, and straighten the ends.