Sorry, that answer was a bit flip, but you did give us some more
information. My joystick (I don't know what one you have) uses the
right/left motion for ailerons and the "twist" motion for rudder. Is
yours one of the old ones that doesn't provide the "Z" axis? Fore/aft
is "X", left/right is "Y" and twist is "Z". If you can set those three
up, you should be able to fly right straight down the runway by twisting
the joystick clockwise a little when you start to drift left.
An alternative \would be to just touch the Right differential brake
until you get enough flying speed for the rudder to take hold.