This was made for a recent swap. I made it from an old charity shop dress that I really liked the fabric off and a scrap of wide sparkley ribbon and a long strip of blue satin ribbon.
Take rectangle of chosen fabric and sew a small hem along one of the long sides.
Have your fabric pattern facing you and fold your rectangle in half and sew along 2 of the sides to make a pocket.
Turn it out so you have neat edges and stitching hidden. Now starting from the mid point at the top edge of your bag, carefully sew your wide ribbon to your bag. You need to sew it at the top and bottom of your ribbon so that you create an space for your other ribbon to pass through. This bit is a bit fiddly.
Tie your thinner ribbon to a large safety pin and thread it through your thick ribbon. Untie it from your safety pin and admire your handy work :).