Just follow that link, or type it in to your safari browser. Then look for the icon that looks like a box with an arrow pointing out of it. Click on that, and select "Add to Home Screen".
The mobile web app stores your login info for one year at a time. So once you're logged in and the web app has been saved to your home screen, you will always be just one click away from the BallroomDancers syllabus.