Install the decorative curtain rod over the window using the hardware included in with the curtain rod. There are usually two or three brackets that install over the window, and the rod rests in the arms of the brackets. The height of the rod depends on preference but should be at least 3 inches above the mounting brackets for the existing curtain sheers or blinds.
Iron or steam out any wrinkles in the wing window scarf. Read the label carefully so the correct heat setting is used for the scarf fabric.
Center the length of the wing window scarf on the curtain rod to ensure the excess length hangs evenly on both sides of the window.
Flip the ends of the scarf over the rod from front to back, leaving a loose swag in the center. The scarf wraps over the rod at the bracket on both sides of the window and the excess length drapes along the sides of the window.
Adjust the center swag so the wings point down and the fabric is gathered evenly across the window. Adjust the draped fabric on the sides as desired; the wings on this portion might be folded back or allowed to point to the center of the window.
Pin the scarf together to hold the pleats in place, if desired, so the wings stay in position. Pin the scarf from the back so the pin is concealed.