What you need:
- Two pieces of fabric 6 by 4.5 inches (or whatever size you fancy really)
- Zipper longer then 6 inches
Step 1: Pin the fabric (wrong side down) to the zipper (right side up). The long edge of the fabric and the edge of the zipper should match with the fabric being roughly centered on the zipper. Sew as close to the zipper as you can get (along what is the upper edge in the photo), backstitching at each end.
Step 2: Fold the fabric back, away from the zipper, and press.
Step 3: Pin the second piece of fabric to the opposite edge of the zipper, sew in place, fold back and press as you did for the first piece of fabric.
Step 4: Top stitch along either side of the zipper. (Not really necessary but I like the finished look it gives.)
Step 5: Undo your zipper about half way (so you can get the pouch right side out after sewing!), fold your work in half along the zipper and pin in place.
Step 6: Sew along the three non-zipper edges, going back and forth a couple times at each end to secure the zipper. Clip the corners and cut off excess zipper.
Step 7: Turn the pouch right side out, press if desired, and enjoy!