Now, as for who they are. Paul was a gaint who was 15ft tall(or something like that). He was a lumber jack who could cut down an entire tree in one swing of his might axe. He is usually seen wearing a red plaid shirt and suspendered jeans. His best friend is a great blue ox named Babe. He and Babe apparently made many of america's landmarks, like the Great Lakes and the Rockys.
And Appleseed was a teenager who walked around this great land(a.k.a America) planting apple seeds and growing trees so people had food to eat. He is seen as wearing overalls and and cook pot(this is a hat, handle going back or to the side).
John Henry was a black man who battled against a machine to dig a train tunnel through the Rockys. John dug with just and mining hammer and spike. He won but died of a heart attack soon after.
I'm sure others can tell you more, this is just an overview.