arduino tank basic move

#define Lpwm_pin 5 //pin of controlling speed---- ENA of motor driver board
#define Rpwm_pin 6 //pin of controlling speed---- ENB of motor driver board
int pinLB = 2; //pin of controlling turning---- IN1 of motor driver board
int pinLF = 4; //pin of controlling turning---- IN2 of motor driver board
int pinRB = 7; //pin of controlling turning---- IN3 of motor driver board
int pinRF = 8; //pin of controlling turning---- IN4 of motor driver board
#define enA 6
#define in1 7
#define in2 5
#define enB 3
#define in3 4
#define in4 2

struct {
  void go_backward(unsigned char speed_val) // speed_val：0~255
  {
    digitalWrite(pinRB, HIGH);
    digitalWrite(pinRF, LOW);
    digitalWrite(pinLB, HIGH);
    digitalWrite(pinLF, LOW);
    analogWrite(Lpwm_pin, speed_val);
    analogWrite(Rpwm_pin, speed_val);
  }

  void go_forward(unsigned char speed_val) // speed_val：0~255
  {
    digitalWrite(pinRB, LOW);
    digitalWrite(pinRF, HIGH);
    digitalWrite(pinLB, LOW);
    digitalWrite(pinLF, HIGH);
    analogWrite(Lpwm_pin, speed_val);
    analogWrite(Rpwm_pin, speed_val);
  }

  void stay() //stop
  {
    analogWrite(Lpwm_pin, 0);
    analogWrite(Rpwm_pin, 0);
  }

  void turn_left() {
    digitalWrite(in1, HIGH);
    digitalWrite(in2, HIGH);
    digitalWrite(in3, HIGH);
    digitalWrite(in4, HIGH);
  }

  void right() {

  }
} Robot;

void setup() {
  pinMode(pinLB, OUTPUT); // /pin 2
  pinMode(pinLF, OUTPUT); // pin 4
  pinMode(pinRB, OUTPUT); // pin 7
  pinMode(pinRF, OUTPUT); // pin 8
  pinMode(Lpwm_pin, OUTPUT); // pin 5 (PWM)
  pinMode(Rpwm_pin, OUTPUT); // pin 6(PWM)
}

void loop() {
  Robot.go_forward(200);
  delay(5000);
  Robot.right();
  delay(6e4);
}