How to transpose piano music to trumpet
All you need to do is to learn and memorize the chromatic scale. Once you are done, you can invert the notes in the piano part up a main second and check the assortment of the transposed part. Check out http://www.ehow.com/how_8541751_transpose-piano-trumpet.html for more particulars.
Bring the key signature and all the notes down a full tone. Pianos are tuned in C, trumpets are tuned in B-flat. :)