how did antonio get rid of his brother prospero and his daughter ? who saved them?how?

Prospero used to be the duke of Milan. Antonio, Prospero's brother, conspired with the Duke of Milan to usurp his throne. They basically set Prospero and his daughter out on a raft to be eaten by sharks or something. Fortunately Gonzalo leaves Prospero his handy magic books. Prospero and his daughter arrive on the island and Prospero sets up his magic kingdom. I suppose Gonzalo leaving the book helped save them but that is about it. Prospero is pretty excited to get his foes close to his magical realm. He creates the storm (Tempest) so he can get them on the island and set things straight.