Before you even take off in World War II Online you have to understand two key concepts: rank and RDP. Rank determines what you can fly. Right now it's a simple and outdated system designed solely to keep newbies from wasting top aircraft while trying to learn to fly. RDP is the system through which new and better equipment, including fighters and fighter bombers, is introduced into the game. There are currently three tiers of fighters - tier 0, tier 1 and tier 2.
Unfortunately, these ideas conflict. Because the newbie rides never change, low-ranking pilots will find themselves facing better and better aircraft as a campaign goes on, while in their very limited aircraft. Worse, the numbers of the newbie rides decrease as a map goes on, in order to make production of newer fighters cheaper. To get around this, you can ask to tailgun for people, or ask them to post missions at the airfield training grounds for the specific country you want to fly for, and spawn infantry there. After 10 minutes, despawn to get a mission success and some rank. However, do everyone a favor and make sure you learn how to take off and land aircraft offline. Fighters are scarce enough as it is.
To ask for these missions or tailgunning opportunities, tune channels 18 and 28 for Axis (18 for the North, 28 for the South) or 55 and 90 for the Allies (55 North/RAF, 90 South/French). Those channels are useful to ask questions on, get help at, get warnings from and find where the action is. Be especially careful of "vulcher" warnings - these tell you that an enemy pilot or group of pilots is hovering near an airfield and picking off those pilots who just took off. If something is on your tail, typically the call goes out "yourname 666". See? The Devil's number has some good in it.
Combat in WW2OL
Air combat in World War II Online is very different from what we imagine. The Allied bombing campaigns on Germany moved the air war artificially high, relative to how it was fought in France, after D-Day, in North Africa and in Russia. The fights are more reflective of those theaters than any stratospheric engagements portrayed in, say, Memphis Belle.
World War II Online's air combat is all about close air support and the interdiction thereof. Bombers spend their time dropping eggs (bombs) on crunchies (tanks) or strafing squishies (infantry and other soft targets). Fighters are there to stop the bombers, but naturally they also end up fighting each other. In areas of air superiority or air supremacy, the fighters will often do something remarkably stupid like descend to the deck, slow down, and go a-strafing. Not that fighter aircraft are ineffective at this duty, just that it leaves them highly vulnerable to incoming enemy fighters who are always inbound. The golden rule of air combat is that there is always someone higher and faster than you. Any enemy that has those advantages is in a position to kill you if he sees you.
Naturally, combat extends itself beyond this scope, as fighters try to stop aircraft on their way to or from enemy airfields (sometimes even strafing them on the airfields, should they dare to risk being killed by AI). Also, there is RDP bombing - the bombing of factories to delay the research of the enemy's new equipment. This tends to move the air war up a bit, but due to poor early warning systems that are easily evaded, it is difficult to spot enemy bombers.