How do I move onto the next session of the course?

To progress through the course you must mark each lesson as complete. If it is a lesson which includes a video, you must watch it to the very end. If it is a lesson without a video, you must click the button at the bottom to mark as complete (shown below). 

Once you complete a session, the next one will be available to you a week after you finish. This gives you enough time to really cement your new practices.