Cover cake with fondant. Any marking and crimping must be done immediately to avoid cracking of the fondant. Mark cake evenly where you want crimping to be. If your crimper has a ring with it, adjust the ring to the desired opening. If it does not have a ring, twist a rubberband over the crimper and use it to adjust the size of the opening. Push the crimper into the fondant. Hold the crimper steady while squeezing the crimper slightly. Continue holding the crimper steady, and let crimper go back into postion. Pull the crimper from the fondant.