There are sop many different ways of doing vibrato on brass, you can either use your lips either as suggested by using the bottom bit of your lip, or by using the corners of you mouth almost producing a lip trill, or by using the diapragm and either moving your bottom jaw slighly, or some people will actually wobble the trumpet slightly to produce the vibrato - you just need to keep trying untill you find the way that you find easiest and suits you,
Yes you can be taught how to do it - but then you develope it in to your own way or technique.
QUOTE(meerkat @ Apr 18 2007, 11:12 AM)

finally, can I just say (at risk of starting a riot) I don't really think some of the comments on this thread have been that useful. I'm pretty sure the OP's teacher is in the best position to decide whether s/he needs to work on embouchure. I'm not sure a couple of lines on the internet is sufficient to comment, and I really don't think it's that fair to undermine confidence in a teacher in this manner, with so little good cause.
It would have been easier to ask his teacher - if he likes the way the teacher produces it then ask the teacher how he does it. Thats wat teachers are for!
Its difficult to give good advice with out knowing the full situation, one simple way of doing things for me could easily cause problems for some one else.
I don't think any one was undermining anyones confidence.