First we need to form our lips into the right shape for making a good tone. This shape is referred to as the embouchure. To create a good flute embouchure, start with shaping your mouth as if you've just bitten into something sour. While holding this position, try to smile a little. You will feel the corners of your mouth tighten.
If your lower lip isn't pulled back, move it back a bit by pulling your jaw back as in lesson 1. The opening between your lips should be small. Test by blowing downwards into the palm of your hand.