Lyrics. Songwriting. Poems. Complicated, right?
Actually, it can be fun.
Once you’ve chosen the topic, you have to summarize what it is you want to say. For instance, if you were writing a song or rap that tells the story of Romeo and Juliet, you’d want to get your thoughts down… at least write a summary of the play so that you know what pieces you want to put into your finished piece.
It might look something like this:

Then, you start changing it — don’t rush, though. You want to keep the meaning of your first draft.