
Read the online manual?
Or alternatively do what I do, go to the controls menu and browse the commands/key settings, lots of good stuff in there.
Off the top of my head, it's ctrl-b to open/close bomb bay. Joystick button 4 to select ordanance, and joystick button 3 to drop ordanance. I think it's F6 or F7 to go to bombardier position, F8 for gun positions, something like that.
And watch out for me ;D
