write a short sports article about the surpise winner of the archery contest at the Ashby Tournament

Do you have to use the characters in Ivanhoe or do you make them up?

I suppose you would want to use the real characters. THe actual tournament happens over a number of days. I would start with something like

Breaking News, Prince John of England presides over the much anticipated Tournament at Ashby.

Then introduce the main players, Cedric, Aethelstane, the Lady Rowena, Isaac of York, his daughter Rebecca, Robin of Locksley and his men, Prince John's advisor Waldemar Fitzurse, and numerous Norman knights.

Then go through the major stuff. Keep it in third person in a news style. I can't write it for you but hopefully this helps a little.