I think you should get online on your own for a while and just have a scout around. Probably better for you to learn the ropes before getting your friend in there with you. Shouldn't take you long to figure out what's what.
It's been a while since I've played multi-player, but if you can't find an empty server for yourselves that no-one else is playing in at the time, there may well be a server running with a map that will allow you both to spawn on opposing sides and then go rendezvous somewhere away from the main action. Easier still if the server rules allow you to spawn at the same airfield and start shooting at each other without punishment.
Never used to be a problem going one-on-one outside of the main action like that, just the opposite in fact, with people always focused on struggling to find the main combat area, let alone looking for side action.
It all depends on the map and the difficulty settings really, but again, it's just a matter of getting in there and making it work for you, then getting your friend in there with you when you're familiar enough with the whole set-up that you can concentrate on helping them out as well.
It might not seem like it, but I expect it wouldn't be long before you're both flying together looking for other players to shoot down.
Actually, forget about the combat. One of the most thrilling and enjoyable things you can do online is to simply complete a 'mission' of your own. Just decide you're going to fly a round-trip to some point of your own choosing (preferably over enemy territory), and then try to do it, knowing you might be spotted by a real-life player and attacked at any time along the way. eg. load up a bomb on your fighter if possible, go drop it on an enemy airfield (or just do a strafing run if you can't carry a bomb), then get the hell out of there. Estimate how much fuel you'll need as well, so you run the risk of running out if you're not careful. The tension as you make it back to home base should be palpable.
Just remembered, as an example of making your own fun, here's a video from the first time I played 'Cliffs Of Dover' online -