The algorithm remains the same - unlikely to help you brute force attack a password in a reasonable time period, thankfully - all you need is to output them differently: instead of Console.Writeline, you need to pass them back to the "calling process" in some way: either by passing a ListBox through to your class (bad), passing each string back to the caller via an event (better), or by assembling a collection of strings which you pass back when you complete (simple, but annoyingly slow to update the display).
To actually display each string is simple:
MyListBox.Items.Add(myNewString);
will do it...