All the printers that you have in windows on this computer should be displayed on this screen.
You should select the printer to use as the default and enter "DEFAULT" in it's 'Output' field.
Read the on screen documentation for further assistance with this option and setting default printers for various forms (such as invoices, statements and purchase orders).
Lots of people ask about printing various forms to screen or emailing them. This is done by installing a fax or PDF printer. See Emailing Printable Documents for details.