First you take a 5 buck memo board from Wallyworld. Try to take it apart, and when that reigns futile, do this.
Sand the veneer off the wooden sides. Paint it black. Add a shiny sealer.
Measure fabric out to the size of the board, to the edge of the frame, as seen in the middle pic. I used a 100 % cotton quilting fabric. Little bit of give, but not too much.
Shove the fabric under the frame with a butter knife. Savage, I know. But it works.
Work your way around, straightening out the fabric so it's good and tight all the way across. You might have to trim excess fabric if you get more than a 1/2 inch to shove under the frame.