I started with a piece of fabric cut to 6"x3"
I also used a small piece of ribbon cut 2 1/2 inches
Fold it in half as shown
Fold in your side seams two times and stitch up both sides as shown.
Next, fold top and bottom (left and right edges) over twice and stitch.
Take your small piece of ribbon and place on good side of fabric with raw edges of ribbon lined up with side seam, it can overlap a bit and pin.
Take your small piece of ribbon and place on good side of fabric with raw edges of ribbon lined up with side seam, it can overlap a bit and pin.
Fold in half good side to good side and stitch up side seams but not to the very edge but to the stitched line from earlier when you stitched the top and bottom edges.
Sew to red line indications, just to where you see the zig zag stichline in the below picture.