I know you are excited to start with your trumpet, but let’s get a few things in place before you pick up your instrument.
Posture and Breathing
In order to play properly you first have to sit up straight. This allows you to breathe deeply and support the sound of your instrument as breath controls all of the sounds you will be making on your trumpet.
One way to do this is to stand up, bend at the waist with your arms hanging loosely to the floor. Now slowly roll up, aligning your spine so it is straight up and down all the way to your head with your arms at your side. Think of a string pulling straight up from the top of your head stretching your body out. Shrug your shoulders up and down, then back and forward. Your shoulders should sit in a relaxed position at rest between each of these places. Now, sit on the front edge of your chair and do the same thing. This puts you in the proper position to support your sound by breathing deeply.
Embouchure and Buzzing
Embouchure is basically, your lips. The trumpet relies on the vibration of the lips to produce the sound. This video gives you some starters for playing your instrument.
Holding the Trumpet
Now that you have basic breathing and embouchure, let’s make sure you can hold your instrument properly.
Your left hand should hold the weight of the instrument with the thumb in the thumb holder, the index and middle finger wrapped around the third valve above the slide, the third finger in the third valve slide ring, and the pinky wrapped around below the slide.
The right hand should make a backward C with the thumb between the second and third valves and the index, middle, and ring fingers resting LIGHTLY on the tips of the valves. The pinky should rest ON TOP of the pinky rest (not underneath). This allows each finger to move the most easily in order to play.
Next bring the trumpet to you, not the other way around. The angle of the trumpet should follow the same angle as when you buzzed with the mouthpiece. This will probably be a slight downward angle, just below parallel, but it should not be pointed down to the ground.