Sainsmart Car 4WD TURNING

I've been having issues trying to get this thing to correctly. Is there something I need to know when trying to make a car turn?

int enA = 10; //RIGHT SIDE
int in1 = 9;
int in2 = 8;
int enB = 11; //LEFT SIDE
int in3 = 12;
int in4 = 13;
void setup() 
  pinMode(enA, OUTPUT);
  pinMode(enB, OUTPUT);
  pinMode(in1, OUTPUT);
  pinMode(in2, OUTPUT);
  pinMode(in3, OUTPUT);
  pinMode(in4, OUTPUT);

void loop() 
  analogWrite(enA, 250);
  digitalWrite(in1, HIGH);
  digitalWrite(in2, LOW);
  analogWrite(enB, 255);
  digitalWrite(in3, HIGH);
  digitalWrite(in4, LOW);
  digitalWrite(in1, HIGH); //turn left
  digitalWrite(in2, LOW);
  digitalWrite(in3, LOW);
  digitalWrite(in4, HIGH);  

Which pin corresponds to which wheel? What effect have the "in?" pins?

How would the car go straight ahead?

How do you want to make a turn? Turn left wheels in opposite direction of the right wheels?