Position the curtains onto the ironing board so that the tops of the pleats are nearest you.
Iron the space between each set of pleats.
Steam the pleats by holding the iron over the fabric and pressing the button that produces a burst of steam. Put the iron down and finish each pleat by pulling the top toward you and the bottom of the pleat away from you. This pulling action will help the pleats hold their shape.
Position the curtain so that the finished pleats flop over the far side of the ironing board. This leaves you with a flat expanse of fabric to press. Iron the rest of the curtain as you would any nonpleated design. That is, press the curtain horizontally, then let the ironed expanse of curtain cascade over the far edge of the ironing board. Iron the next horizontal section of curtain. Continue until you have pressed the entire curtain.