How do I organize my references in to collections in Mendeley Reference Manager?

There are currently two ways to add a reference to a collection:

1. Drag and drop a reference in to a collection in the left hand navigation panel.
2. Select the check box next to the author name to open the Action Panel, select 'Organize', select 'Add to Collection', then choose a collection.
3. Drag and drop your top collections onto another to convert it into a nested collection, you can also drag a nested collection onto the ‘Collections’ heading to convert it into a top level collection.