Measure wrist with a tape measure; add 2 1/4 inches, and cut a length of ribbon to total.
Run ribbon through slot on one side, over back of watch face, and through other slot.
Fold over 3/4 inch of ribbon on each end; iron flat. Use a hammer to attach snap fasteners to each folded-over side, following package directions. Be sure the female half of the snap faces down and the male half faces up, so they close properly when placed on wrist.
Replace a broken or worn-out watchband with grosgrain ribbon.