Here are the steps to make a window valance:

1. Measure the width of the window frame, adding two inches to each side.
2. Buy a 2x4 for this length.
3. Attach hook and loop tape (smooth side) to the front and ends of the 2x4. Secure with a staple gun.
4. Install angle brackets on each side of the window frame, flush with the top.
5. Cut fabric to size.
6. Fold over the top edge of the fabric and sew it down.
7. Slide the fabric onto the 2x4.
8. Hang the valance by placing the 2x4 onto the angle brackets.

You can find more detailed instructions on how to make a window valance at and . I hope this helps!