Instructions
Sit or stand up straight so you are able to use your full lung capacity. Your lungs are unable to expand to their full size when you slouch over or when you lean back in a chair.
Purse your lips together. Imagine you are about to blow something through a straw, or perhaps that you just bit down on a particularly sour lemon. That is approximately the type of purse you want to get on your lips.
Blow out through your pursed lips while maintaining the pressure of the purse. You want to create a wet "raspberry" sound with your lips. This is the tone that will come through the instrument.
Place the instrument's mouthpiece over your pursed lips. Push your lips into the mouthpiece so they are firmly in place, but not so hard that you are mashing your lips against the metal.
Blow into the instrument's mouthpiece.