You can add sub sections to your curriculum for your courses in the following steps:
1. Click on the Commerce tab on the left side bar and click on Courses.
2. Click on the Add a Course button and add your course details in the window that pops up.
3. On the Details tab, enter your subtitle, select an instructor, category, description and tick the box if you want the course featured or as a standalone course.
4. Populate your Branding and SEO tabs.
5. Next, click on the Curriculum to the left to start adding sections, lessons and content.
6. Add your main section to the curriculum and then add your lessons, quiz or assignment.
7. Under your main section, you can click on the add sub section button to add a new sub section.
8. Add new lessons, assignment or quiz to your sub section.
9. Publish your course when you are done.