Step 2: Sewing the top with the drawstring
This can be done easily with a sewing machine, too, but I don't have one of those. I like to get down to the basics as I'm a bit of a rugged sort of chap. :D
This line of thread you'll want to do the most carefully as it is the only one you'll see when it's finished. I found this out after I'd done it but hey ho, we learn from our mistakes. ;)
After you've gone across to the end, go back again to fill the gaps, as seen in the third piccy.