Lay the curtain panel on a flat surface, right-side down. Find the pinch pleats on the back of the header of the panel. Each pleat consists of gathered fabric, securely tacked or sewn together with several wraps of thread, typically about 3 inches from the top of the panel.
Insert the curtain pins, working from one end of the panel, toward the other. Hold the pleat in one hand so the lower end of the curtain is on the bottom and the header is at the top. In the other hand, grasp the curtain pin. Hold the downward-curving unsharpened portion of the pin between your thumb and forefinger. The sharpened end of the curtain pin is facing upward.
Push the sharpened point of the pin into the pleat, just below the tack where the pleat is sewn together. Turn the curtain pin so the sharpened end points toward the top of the curtain. Push the sharpened end of the pin through the tack, until the curve in the pin prevents you from advancing it further.
Repeat to install the remaining curtain pins.