I know, I know: These are everywhere. Now to toss mine into the fray: ultra-simplified and with pics for every step.
1
Gather your materials.
2
Dismantle picture frame.
3
Use glass to trace shape onto plastic grid (I got mine in the embroidery section of the craft store). Cut out grid into final shape.
4
Hot glue the grid to the wooden part of the picture frame. Be messy, no one will ever see it!
5
Hot glue ribbon to the corners and let dry. Done!