Match the two straps on one side on top of each other. Starting 2" from the bag edge (be sure bag is completely open !!), stitch all the way to the knots. Repeat on the other side.
On the front side of your bag (the side with the pocket, even though my bag doesn't have a pocket LOL), match the strap to the same side at the bottom bag edge. Place the bottom of strap diagonally in corner and double stitch. Repeat on other side.