I can give you a brief overview of the play, but I strongly suggest you go to the link below to get the full description of the events and characters.
Caesar's ambition to become the ruler of Rome is interpreted by some as his desire to be a king or a dictator. Caesar is warned to "beware the Ides of March" from the beginning. Brutus, Cassius, and others secretly conspire to assassinate Caesar on the aforementioned date. Marc Antony comes to Caesar's defense after Brutus tells the crowd that Caesar's ambition would have ruined Rome. It is then that Antony gives his famous speech beginning with "Friends, Romans, and countrymen...". The remainder of the play is spent on the battlefields between the conspirators's forces and the forces of Antony. In the end, all of the conspirators are killed for their betrayal.