A ballad is one way of telling a story. Prose is another.
In a ballad, lines are often similar length and often rhyme. Prose is more like regular speech. If you use prose, you just write normally.
For this week’s prompt, take last week’s story. Using “The Ballad of Roselyn” as a guide, write a prose story of Roselyn’s adventures – or continue the story in ballad form. You can change anything you like (maybe Rose isn’t a princess, or it’s her mother who finds out that Rose wants to capture a dragon – would she react differently?) but try to follow the overall story arc. Enjoy!