How to fly a plane
If you find a plane on the ground you can choose to board it, you will then need to start the engine pick up some speed and once you have enough speed you will be able to take off the ground, and to land you just need to slow down your engine when approaching the ground. But more likely than not you will spawn in a plane that's already flying, to control the plane you have to move your mouse which is going to behave as the nose of the plane (Notice: you can change this in the settings) To open fire you just need to hold left mouse button, you can switch type of weapon by scrolling with your mouse wheel, and you can drop bombs by using "Spacebar". Once you run out of ammo you will need to refill for that purpose there is usually a plane repair point somewhere in the map that once you pass it will restock all of your weapons and repair your aircraft if it was damage. And whatever you do, don't click "E" while flying!