If you have an afghan that you'd like to display on a wall, don't use nails or hooks, which can stretch and distort the fiber. Instead, use a wall-mounted quilt hanger.
Things You'll Need
Mount the wood quilt hanger to the wall. Secure it per the manufacturer's directions. Put a level on the top and check it before drilling any holes.
Fold the afghan in such a way to display its design optimally.
Slide the top edge of the folded afghan between the two horizontal strips of wood. Adjust the afghan to the desired length.
Tighten the screw at either end of the wood strips. As the screws tighten, the afghan will be clamped between the two strips of wood so it can't slip off the hanger.
Have a second person work with you. As one is positioning the afghan in place in the quilt hanger, the other can be standing across the room checking that it looks right.
Don't overly tighten the screws on the quilt hanger. You don't want to crush the fibers, leaving a dent. Just tighten them enough so the afghan can't slip off the hanger.