This is what it looks like opened up. The strap going across the middle gets pulled through two tabs, one of which you can see at the bottom of the picture.
This project has been sitting on my project table since last October! I made one for myself back in October when my MIL was visiting and could offer me her sewing expertise as I needed it! She was quite taken with the carrier idea, so, of course, I told her I would make her one. I might be slow, but I do remember what I promised! I found this project in Quick Quilts, #117. I also made her a coordinating card!