You can create collections (folders) within your library to organize items associated with different topics or projects. Just drag items from the center pane over a folder to add them to a collection. If you select a collection before searching for sources, any items you add with the connector will be added to that collection.
Note that items added to a collection will still appear in you main library. Collections work more like playlists than file folders.
With an item selected, you can use the icons on the right-hand side of the app to add notes about the item, or to add tags (keywords) you wish to associate with the item.
The Search feature offers several options, so be sure you know what you are searching!
The advanced search feature allows you to search on specific fields and combine multiple criteria. You can also save a search. The saved search will appear below your collections, and new items that match the search will automatically be added.