Sorting and Searching:
Collections allow you to categorize your citations. They show as folders in the left column as folders:To create a new collection (or sub-collection) click the New Collection icon.
You can add items to collections by dragging them from the center column. (Note: items can be included in more than one collection)
To display the items in a collection, simply select it in the left column. The center column will then only show the citations in that collection.