This function has really nothing to do with the application, but since you probably have your whole client list on this device, it will useful to add information about your clients, or a quick to-do list for the client etc. To use it, just click on the button like the one above, select the date range of the note and if it should be sorted by date or client, and press "Ok". A database search will be done, and the notes will be displayed. There will always be the 
button that allows you to add more notes. You can click on a displayed note to modify the note or delete it.