For a "Mountain fold," ford the paper away from you, so that the fold is closer to you. For a
"Valley fold," ford the paper towards you, so that the fold is farther from you.
When finished, the plane should have four half-trapezoids forming right angles. If two of these
are taken as wings (with the shorter edge in front), the one hanging down is the body.
Hold the body of the plane at the bottom, push forward, and release.
If the plane doesn't seem to be flying, try sharpening your creases.