The best way to start is to read the manual, where pushback, configuration of airplane and stand are explained. You first need to understand how GSX works, then you will see what you need to do for a certain airport. I also can suggest the LSZH Files from cartayna. Youll find he's facebook link in the config section for the airports. he has a great config for lszh. When you see a jetway appear when you call gsx, it is clear you won't see stairs on your front door, because then gsx assumes you use the Jetway for boarding. Those are all things explained in detail in the manual. And there are also GSX Tutorials in youtube, that are very clear and helpful.