2. Place your left thumb on the first valve slide trigger. This trigger is located on the top of the horn, just above the first valve slide.
3. Press down on both the thumb key and the first valve slide trigger. This will open both the thumb valve and the first valve slide, allowing air to flow through them.
4. Blow into the mouthpiece. The air will flow through the thumb valve, the first valve slide, and out the bell of the horn, producing the note B.
Here are some additional tips for playing B on the French horn:
* Make sure your lips are buzzing properly. The buzzing sound should be even and consistent.
* Blow into the mouthpiece with enough air pressure. The air pressure should be strong enough to produce a clear sound, but not so strong that it makes the horn sound harsh.
* Hold the horn steady with both hands. This will help to produce a clear sound.
* Practice playing B until you can produce it consistently with a clear tone.