The picture below shows a modified version of Bernoulli's equation, including energy per unit volume. It explains the how pressure and velocity are affected as liquid moves through a tube with segments of different area.  The fundamental rule shown here is as the speed of a fluid increases, its pressure decreases.

bohr.physics.hku.hk/.../ lectures/chap02.html

Now we can apply this rule to a wing traveling through air, otherwise known as an airfoil.  When an airfoil is tilted upwards the air above the airfoil travels faster than the air below the airfoil because it has a greater distance to travel.  The higher velocity above the airfoil creates a drop in pressure and the lower velocity below the airfoil creates an increase in pressure.  This results in a "push" from the bottom otherwise known as lift.  Since the wing is also angled upward a downward push is created from the trailing edge also pushing the airfoil upward.  All of this allows a plane to fly.  More efficient designs in wings have been made to allow maximum lift for different types of planes.  This is discussed on the next page.