The body of the screen is a list of the hymns in the current hymn book.
Select a hymn by clicking on it, and then clicking the "Ok" button.
Double clicking on a hymn, does the same thing.
Multiple hymns can be selected before clicking the "Ok" button.
The "HymnBook" button opens a dialog to select a hymn book.
The "Help" button, shows this screen.
The "Cancel" button, closes the screen, ignoring any changes.
The "Ok" button, closes the screen, saving any changes.