How do you get to be a Jedi in Battlefront 2

Once you get so many points or the timer reaches, it will ask you if you want to play as the hero. Say yes, and you can launch as the hero. Note: Most heroes are Jedis, but some aren't. For example, there's Jabba Fett and Chewbacca. The reason I mention this is because you asked on how to be a Jedi.