After you've created a list and associated it with a course, you can create sections within the list. These sections can be for particular weeks of the course or specific topics. 

Step 1

On your reading list, click on "New Section"

Step 2

Add a title and click Create:

Note: if you prefer, you can add a description to the section or set due dates.  if you choose, you can also decide to hide sections as soon as the due date has passed.