For a really good explination of how a plane flys, how to turn, and so on, I think this is one of the best websites out there:

"How it Flys"
http://www.av8n.com/how/

This site is aimed at private pilots, and you can ignore a lot of the site, when it goes on about what to look for when looking out of the airplane from inside. But their aerodynaics are non-technical, very readable, and the application applies to models as well as full-scale.