Hang the drapery wrong side out, the right side toward the window, for ease of sewing. A better result is achieved if the stringing is done while the drapes are hanging.
Pin one end of a 20-foot piece of drapery cord to the middle of each center edge.
Drape the cord away from the center, toward the curtain rod. The drape of the cord will mimic the shape of the swag formed as the drapes open. Adjust the drape of the cord until the desired swag shape is achieved.
Pin the cord to the top of the drape at the desired position.
Mark the positions of the guide rings. Start at the middle of the center edge of one curtain half and fasten safety pins, through all layers of the drapes equidistant along the cord, every 4 inches. There will be excess drapery between the pins that falls to the front.
Sew a ring to the drapes, through all layers, at each pin position. Sew a ring, every 4 inches, along the top of the drape toward the outer edge from where the cord is pinned to the top edge.
Unpin the cord from the drape. Tie it to the center edge ring, run it through all the rings and up to the curtain rod. Thread the cord through the rings along the top, to the outside edge.
Let the excess cord fall toward the floor along the outside edge of the drape.
Make, or purchase, a small fabric bag to hold 4 drapery weights. Sew the bag to the inside of the drape at the position of the first ring. This provides weight to help the drapes fall correctly when being closed.
Rehang the drapes, wrong side to the window. Draw them by pulling the cord; the swag will form, and they will open. Secure the cord by wrapping it around a cord cleat fastened to the wall.