I just wrote a whole song and then found out you can change it to trumpet so is there anyway I can change from Piano to trump...

Hi.

Congratulations, you must feel terrific. :)

It's a real accomplishment.

Sure, just right click the staff, Staff Properties, then Change Instrument, and select trumpet. Note that trumpet is a transposing instrument, so the music will automatically move up a step so that it will sound the same.