Now that you've got the hang of making the knit stitch, just keep going until you want to call your work finished.
For me, I knit until the project was about square, which was about 38 rows, but you can make yours as long or short as you like.
If you're getting holes in your knitting you might want to count the number of loops on your knitting needle every few rows to make sure you've still got 20. For this project it doesn't matter if it gets a little wider or a little narrower, but the goal is to keep the same number of stitches you started with as you go through the project.
