Hit and run misdemeanor in California

One year ago during my high school year I hit a parked car and ran away. A week later passed and they caught up to me and I never got arrested for it. They said they had to write it down because I ran away but the person did not want to charge me. I paid them for the damages and we signed a contract saying we paid them (homemade contract). A year passed and I got letter about my arraignment hearing and I’m nervous. What should I do? What do you guys think is going to happen?