First I cut out the pattern and marked on it where I was going to sew, using the clasp to check where to stop sewing the base of the bag together.
I also sewed the lining and a piece of calico together (the lining is a thin muslin so I backed it with some calico)...
... and mitred the corners of the lining and bag material.
Here's the finished pouch. It's about 6 inches wide. Aside from help in the bag-making course at Morley, I also followed the guidelines of this great online tutorial to make the bag:
I haven't included full details here of how I made this clasp pouch, but if you go to that tutorial, it has great guidelines.