If you enable reading lists in Canvas and there no reading list associated with your course already you will see a screen like this:
When you click "Create It" you will be taken through the steps to create a new list associated with this course. You'll give the list a name andd a description if desired. You will be able to select from a list of templates with pre-built sections for organization (which you can change later). And then you will be able to start adding items to your list.
Work with an existing list
If a reading lists already exists for your course because the library has added course reserves or textbooks owned by the library, the list will appear in Canvas if you enable it. After you add the reading list element to the course navigation and click on it, the list will automatically appear. Make sure the list is published if you want students to be able to see it. You can continue to add items to this list however you would like using the blue button with the plus sign (.