Firefly Main Title by Greg Edmonson is in C at 85 beats per minute and runs 0:49 across 12 bars. It uses 8 chords — C5, F, Gm, Eb, Bb5, F5, Bb, Eb5. The chord diagram changes as the song plays and the words light up as they are sung, so you can strum and sing along without reading ahead.
Want the melody line note by note? Firefly Main Title guitar melody tab.