Mount one single pulley at the top left side of the curtain area. Screw a long wood screw through the pulley mounting hole into the post or wall stud with a screwdriver. Mount one double-double pulley at the top right side level with the left pulley. A double-double pulley consists of two sets of double pulleys mounted so that the top pulleys are close to the bottom pulleys. The pulleys should mount through the side with the side facing you. The cord will always be on the side with the double-double pulley.
Screw a small screw eye -- a screw with a loop instead of a screw head --into the post or wall to the left and centered on the double-double pulley. Mount a tension pulley below the double-double pulley approximately 12 inches off the floor. Tension pulleys are found with most curtain supplies.
Thread the cord up and over the top of the left side pulley, over the wall side of the top right pulley and down to the tension rod while staying to the outside of the tension pulley. Take the cord under the tension pulley to the inside and up so it crosses over to the outside of the bottom pulley closest to you. Thread the cord between the outside top and bottom pulleys from the right toward the left. Bring the cord to the left.
Pull the cord tight and knot the two ends together so that the knot is on the bottom level of the left side pulley. Attach curtain rings with alligator clamps over the lower cord. Place one curtain ring to the left of the cord knot. Sew the top of this ring to the cord with needle and thread.
Place one curtain ring attached to the screw eye on the right post. Use one curtain ring for every 6 to 8 inches of curtain. Attach the curtain to the alligator clamps. Attach the left side of the curtain to the clamp of the ring sewn to the cord. Attach the right side of the curtain to the clamp of the ring attached to the screw eye. Operate the curtain by pulling on the cord on the right side between the double-double pulley and the tension pulley.