Here's a very simple and fun bag. I have never seen the directions for the humbug bag, but I assume it would be quite simular.
I started out with two fabrics and a cotton batting cut 12" X 9".
With the three layers, I free motion quilted them together and used a serger to sew all 4 sides. Sew the zipper on with the zipper face down on top of the right side of the fabric. Note I was using a zipper too long for the bag, but it doesn't matter because it can be shortened when we sew it in the seam.
Now turn the fabric so you can top stitch along the edge of your zipper on each side so that it will lay flat.
Now turn your fabric with right sides together and stitch the bottom of the bag across the zipper and trim off the excess bottom.
Use a ribbon and tack inside the top portion of your bag and sew the bag the opposite of the direction from the bottom. Turn right side out. Add a zipper pull if you wish.
Simply hang your bag when not in use.