If you want to add any embellishments, such as the button and velcro I added to my purse, simply use a needle and thread. For a less durable finish, you could use craft or fabric glue.
Now remember back to the beginning of this tutorial when I said I wanted to make a bag large enough to serve as more of a tote bag than a purse and then look at my finished project above... and learn from my mistake. I should have started out by making a swatch and testing how this yarn shrank, I would have then known I needed to adjust the pattern much more than I did. I also would have made the strap narrower. Live and Learn!