Merc501st

Hello! Me and my friends usually play a CTI game in Operation Arrowhead (just OA) with ourselves. We would get the Helipad up and running, but We dont know how to "upgrade" the Aircraft Factory. It was surprisingly hard to find any information on this. When ever there was information, vague instructions were given. Please, we want to fly some planes! So if you can, in a CTI match, build and fly aircraft in the airports? Or do I have to edit things? How do I upgrade the factories? If there are any special key bindings, let me know. We arent very intune with the specifics of the game, but any information would help. Thanks!