Hold the mouthpiece gently between the thumb and the indexfinger close to the end of the shank.
Buzz a G (find the pitch first) and place the rim first on the lower lip and then move it carefully up so it contatcts the upper lip. Keep a steady lip buzz while doing this - then make a seal so the buzz goes into the mouthpiece. Hold this mouthpiece buzzing sound for 3 counts. Then take the mouthpiece completely away and rest.
Repeat several times with this G.
When this works smoothly, try to descend to F, E, D and C as shown above.