The explanation of the keys gets on the screen , I push ok and then there happens nothing .
If you really did exactly what you just wrote, it's normal nothing happened, since you did nothing. The ENTER ( not Ok ) key is used to exit from the editor but, it doesn't seem, according to your report, you did anything with the editor so, you just entered it and exited it.
When you exited it, it would return to the 2d editor dialog window and, while that is open, the GSX menu will always show "Loading", because you can't use GSX while you are editing stuff. So, perhaps, the window might have been gone behind the simulator window and you haven't noticed it, so you assumed the program was stuck, when in fact was just waiting you to exit from the editor dialog window.
Try editing the parking in windowed mode, not full screen, so it will be more obvious ( even with the help of the taskbar icons ), which windows are open.