To move a reading, hover over the reading and click and hold the blue panel that appears on the right side of the citation. You can then drag the reading to anywhere in the reading list, including a new section.
To create a new section, click on the "New Section" button at the top of your reading list, add a title, and hit "Create".
If you would like to change the title of an existing section, click on the three dots (the "meatball menu") at the top right of the section and click "Edit Section".
To edit any of the citations, click on the meatball menu beside the citation and choose "Edit Item". From here, you can also add a public note to your students that appears with the reading.
Use the "Add Tags to Item" option to tag the reading Required, Supplemental, etc. You can add multiple tags to an item.