Citations can be edited by clicking "..." on a citation, then "Edit Item". This allows you to, for example, edit the item's metadata.
Clicking on an individual citation expands it, allowing you to add Due dates to citations, or add notes for students:
Citations can also be dragged and dropped into different weeks. For example, clicking and holding the drag option on the citation in Week 1 and moving it to the Week 2 section will change the week it is associated with: