I was just wondering how to transpose music. Lets say from C m(flute, piano) to Bb (clarinet, trumpet, tenor etc) or something. Does that make sence? If it doesn`t, please reply and I will get more detailed.

Yes, It makes sense. Let`s put it this way. A when a flute plays a B flat, it`s in concert pitch. A clarinetist would have to play a C natural to get the same pitch. In short, bump all your concert pitch notes up a whole step (2 half steps). Using a piano is helpful.

This subject bugs me like mad, need to have a drink to calm me down. In the ABRSM exams they write about 4 - 6 bars of music and say something like:-
"This passage is written for the Clarinet Bb. Transpose this down a major 2nd as it will sound at concert pitch - remember to put in the new K/sig."
My teacher told me the approach is: 1. Add new K/sig
2. Lower notes dowm a 2nd & 3. Change accidentals.
I can lower the notes a 2nd and change the accidentals, but how do i know which K/sig to transpose to?
E.g. This particular passage had a k/sig with one # in it & my teacher instantly writes in a k/sig with one b.

DOES ANYONE KNOW HOW HE TRANSPOSES THE K/SIG OR ANY WAY WHICH HE FINDS THE KEY HE WANTS TO TRANSPOSE TO?
I would really really appreciate any help given.

Simon- key signatures
C= Bb
Db=B (or Cb, but that key should not be allowed to exist, in my opinion)
D=C
Eb=Db
E=D
F=Eb
F#/Gb=E
G=F
Ab=Gb
A=G
Bb=Ab
B=A
It is just the same as for transposing the notes.