Once you've enrolled in a class you can find your class content under "Your Classes." When you sign in "Your Classes" should appear on your home page.
To navigate from a different page to "Your Classes," click on your profile in the top right corner and select the class you'd like to view in the drop down menu.
Once you are on your class page you will find the lesson plan for your class. Select the lesson you'd like to view and you'll be navigated to the selected lesson where you can view content, review the workbook, and participate in the lesson discussion.