Most likely, you should just play the music as it is written as music written for Trumpet most often means Bb trumpet. There are trumpets made in the keys of C, D, Eb and other keys, but most often it’s Bb for popular music.

If the music is written in Concert pitch, that means written for C instruments (i.e. Piano, strings). In such instances, since a Bb is one whole step below C, we should play one whole step higher than the music is written.

So, in the example above, you would play starting on a G, not an F#, and the key would be G (one sharp, F#).

Hope that helps clarify. Good luck and have fun–learning how to play melodies you like is a big part of the fun and development as a player.