Depends a lot on the Joystick. A proper flight stick has forward/back left/right movement as usual but the stick should have a 'twist' function.
Often called 'Z' rotation. This gives rudder action independent of banking. When your on the ground this also enables steering. Plug in usb stick, start game, go to settings, other settings, controls, calibration (ensure Enable Controllers is ticked and stick is identified correctly), click on calibrate and it should show if you've got 'Z' rotation for the stick.
If not, you can assign keyboard buttons for rudder movement by going back to Controls and selecting Buttons/Keys and editing them. I'm not sure but I think default keys for rudder controls were on the Numeric Keypad.
Best of Luck the Microlight/Ultralight is the easy one, it's a steep learning curve!
Suggest also your Father join a relevant forum for help and info, loads on assistance there as well.