Count the number of pleats on the drapes, and purchase this number of pins, plus two extra pins per drape. Each pleat requires a ring or carrier on the rod. The number of pleats and required rings would typically be calculated before construction but, for ready-made drapes, you may need to add more rings or carriers as necessary.
Measure from the bottom of the eye-screw -- which is inserted into the bottom of the ring for drapes hanging on rings -- to the bottom of the ring and record this measurement as the "pin drop." The pin drop measurement on rods with carriers is the distance from the hole in the bottom of the carrier to the bottom of the rod.
Measure the length of the drapery pin. The pin is shaped like a backward “N”: The left arm is pointed at the top and the right arm is slightly curved out at the top, curved in halfway down the length and then out again at the bottom, creating a soft backward “S.” The length is the measurement of the straight left arm. Drapery pins for pinch pleats are available in one shape and two sizes: large for curtains or drapes and small for sheers
Add the pin drop and pin length together. This is the "bottom of pin" measurement.
Measure from the top of the drape toward the hem and place a mark on each seam at the back of each pleat equal to the measurement of the bottom of pin measurement.
Place the bottom of pin marks on the outside edges set in from the edge by the amount of overlap required for the drapes. There can be no pins in the overlap area or it will not overlap. This amount, determined at the time of construction, is usually one whole space, but it could be as narrow as the width of the edge hem only, in which case the pins would be set at the inside edge of the side hem.
Insert the pointed end of the left arm of the pin into the drape at the bottom of pin marks. Insert the pin all the way into the channel of the pleat, through the seam line, leaving the center bar and right arm of the pin exposed. Insert all the pins across the drape.
Gather the drape along the top and lay it over your right shoulder with the right side on top. Insert the pins, starting with the far right pin into the far right carrier, or ring, first. Insert the second pin into the second carrier and continue inserting pins into the rings or carriers along the rod. The drape should stay in position over your shoulder. This prevents excess weight on any carrier until all the pins are in place.