The physics simulation does not simulate aerodynamic forces, so you will have to apply those to your instance yourself. To apply lift, simply apply upward force to the wing. If you apply the same force as your gravity, the instance will hover, and if you apply more force than gravity, it will rise. Add a horizontal force to act as thrust and you are flying (upward)!
That's the concept at its simplest. You can get as complex as you want, by adding drag, incorporating angle of attack, variable thrust, etc. If you just want to make a basic plane or glider, then you can get away with just doing this to your glider instance. If you want to make a more complete simulation, you will have to think about applying some or all of these to every dynamic instance in the physics world. This would not be difficult to do with proper parenting (which you should be doing with physics anyway), but it does require some more planning on your part.
Now, if all that helps, great! If not, then you may need to familiarize yourself with the basics first. In that case, start with
this tech blog, and go through all four parts. This
post is also helpful to decide if you even need to use the physics system.