I'm not going to explain all details of principals of flying.  This information is presented in many places on the web - just type in Google: "How airplanes work" and you will get thousands hits.  I would rather take a simple approach that you don't need p.h.d. to understand it. It's important to remember, that the magic number to flying is "4". It is true for most full scale planes as well as for radio controlled models.

Go to:  Magic number 4 - part I ...