Take your pillow case and cut it down both sides.

After you cut the pillow case lay it flat and center your throw pillow on it.

fold one side of the pillow case over the pillow and cut four strips in it, do not cut them to deep.

Remove the pillow and fold the pillow case in half, the cut similar strips into the other half of the the pillow case.

center the pillow inside the pillow case again. Take a strip from each side and tie a bow like this.

if you want you can sew this top part here but i just left it open.
and your done!