What Should I Do?

Me and my gf were driving and some idiot trying coming into my lane and hits the front left side of my car. I slammed on my brakes when I saw him coming in my bubble and I jolted the car to the right to evade. My gf said that she heard them hit my car and at the time I did not hear any thud against my car so I thought it was a close hit but no contact. After the car hit me they tried dashing away but I got behind them and my gf took a picture of their license plate. We went home and then I saw that they actually did hit me. What would be the course of action from here. (note damage to car is very minor small dent and small groupings of scratches)