From the RealFlight Launcher, press the button that says, 'additional options'.

That will bring up some buttons. Press the one that says, 'Registration/Updates'.

A dialog box will pop up. Press the button on it that says, 'Update to latest version'

That should do it.

If you're like me, you recently got the software. The recent boxes have the most recent software in 'em. If your box dates from when G3 was very first released, then you've got a lot of updates to download when you press that third button. (It was released way before it was ready. Like that EVER happens in the software world. )

There ya go.