You can both add existing Pieces to a Setlist and files directly from your Drive, Photos or blank templates. 

There are several ways to add Pieces or Files to a Setlist: 

• From a Setlist: click the “+” icon in the Setlist header and select your Piece(s) or File(s) using the blue checkboxes on the left
• From My Library, with your list of Pieces open: click on “Edit” in the top-right corner of the screen, select your Piece(s) using the blue checkboxes, click on the black circle icon in the top-left corner and click on “Add to setlist” 
• When importing a Piece: when you create a new Piece from the Import menu, you will always be presented with the option to add it to a Setlist