Start with the tutorial bits (up till TheFirstVehicle). I know that's about a train, but the basics are the same. Once you understand the basics, the rest will become more clear. You don't need like 90% of the specification to get your aircraft working.
So yes, do a train first. You don't need to draw one; either knock out some box shapes or copy some sprites elsewhere.
As soon as you're stuck on something: ask. Then follow the same basic strategy for your aircraft. And again when your stuck: ask.
Make sure though when you ask that you specify exactly where you're stuck and what you don't understand. That way you'll get the more useful replies.
Good luck!