Once you have all the pages created that you need, click on the NAVIGATION button in the left-hand column pane.
At this point, you might need to create a Default page to use as parent for your lesson pages.
Side note: It's a good idea to have an index or default page for your main content folders. Not only will you have a parent page to use for navigational purposes but you'll have a site itself that is easier to navigate.
Now you can drag & drop your pages into the navigation scheme desired.
