Pick up your trumpet.
Place three fingers over the three keys on your trumpet.
Press down the first two keys on the rumpet. Blow the trumpet with a medium stream of air. You should be blowing an "E." If you blow too slowly, you might get a low "A." If you blow too hard, you might get a higher "A.. You will want to blow at a speed in between so as to not under or overshoot the note.
Release the middle key only pressing the first key. Blow into the trumpet at the same pressure you did before. You will hear an "F," "E" and "F" are a half-step away from each other.
Blow through your trumpet and rapidly toggle between your "E" and "F." You will hear the classic musical sound for buzzing.