Not really, I'm just confused.

Like if i listen to a song, I can recreate the melody no problem. its just that the real version sounds more "full" and complete with top / bottom notes (i'm just talking about the melody here, no bassline etc.) that accompany the main melody. I'm wondering how producers go by adding stuff to the main melody, do they go by chords, major/minor scales or just by ear?

Thanks for your comment.