If you have a joystick with a rotating stick this is the way, if not maybe you should setup the keybord for rudder control. In any case when running a game (you are in an aircraft) press F10 o bring up the kneeboard and go to the commands tabs (the first one). See if there are already defined keys. I use the joystick for this and I am not at my PC now, so I cannot tell you for sure.