Fleeing or eluding without lights siren?

So i asked a previous question about getting a fine to eluding a police officer. At first it was a misdemeanor, Now i got a letter in the mail saying it has been bumped up to a criminal charge and my court date has been changed with a different judge. Also the letter stated my charges and it says fleeing or eluding without lights siren. What does that mean? What should i do, get a lawyer now.