Originally Posted by Patric_Bernard

and add two sharps/take away too flats. However you want to think about it. So if your playing in F. Lets say for trumpet. so you ahve one flat, and you want to transpose it to C, you would move every not up a whole step and you would add two sharps. So one sharp would make it C, and another would make it G, with one sharp.

To read Music in Bb, that is written in C. you do the opposite, move everything down a whole step, and take away two sharps/add two flats.