Admins can edit the order of Lessons in a Course. This "ordering" determines how lessons are displayed in the Course page of the User Portal.
This article outlines the following concepts:
Course Editor
Go to Learning > click Courses > select a Course
Content tab
Go to the Content tab. The Lessons contained in this Course are listed.
Manually change the lesson order shown to learners by dragging the Lesson to the desired position or typing the order number. Admins must click Save to lock in any edits to the lesson order.