To manage your lessons, click on your username in the top navigation bar to get to the your lessons page. On this page you should be able to view all the lessons you have made.
You should see links labeled "Review Student Work" underneath the video image for each lesson that students have posted replies to. Click this "Review Student Work" link to see information about student responses. You can see students' names, a record of their activity, and their responses to questions. This information is also available as a CSV. Inactive students will appear in a separate list after active students.