As I was making a left hand turn to enter a parking space the driver in the car in the next parking space opened his car door and I hit jt when I enter the parking space. Who is at fault?

Possibly equal fault, but frankly I think you may have been at greater fault. When you started to enter the space, you should have noticed that there was someone in the car and you should have anticipated they might want to exit. And, it5 would seem you were going too fast if you could not have stopped when you saw the door open.