I cut out the main fabric pieces for the outside of the bag, lining pieces, and heavy weight fusible interfacing to give the bag some stability.
I placed the lining in the bag, right sides together, then sewed the lining and bag together around the top, leaving the space between the straps open. I then turned the bag right side out and pushed the lining to the inside. I hand stitched the opening, then machine top stitched around the top opening.
I am fairly satisfied with the end result, but I think next time I will make the block/pocket smaller. Instead of 10" x 10", I will make it 8" x 8". I think that will work much better.