#define led1 13
#define led2 12
#define led3 11
#define led4 10
#define led5 9
#define led6 8
#define led7 7
#define led8 6

void setup() {
  pinMode(led1, OUTPUT);
  pinMode(led2, OUTPUT);
  pinMode(led3, OUTPUT);
  pinMode(led4, OUTPUT);
  pinMode(led5, OUTPUT);
  pinMode(led6, OUTPUT);
  pinMode(led7, OUTPUT);
  pinMode(led8, OUTPUT);
}
void loop(){
  digitalWrite(led1, HIGH); //this will turn on the 4 green lights.
  digitalWrite(led2, HIGH);
  digitalWrite(led3, HIGH);
  digitalWrite(led4, HIGH);
  digitalWrite(led5, LOW); // this will turn off the 4 red lights.
  digitalWrite(led6, LOW);
  digitalWrite(led7, LOW);
  digitalWrite(led8, LOW);
  delay(5000);  
  digitalWrite(led1, LOW); // this will turn off the four green led.
  digitalWrite(led2, LOW);
  digitalWrite(led3, LOW);
  digitalWrite(led4, LOW);
  digitalWrite(led5, HIGH);//and will turn on the 4 red lights.
  digitalWrite(led6, HIGH);
  digitalWrite(led7, HIGH);
  digitalWrite(led8, HIGH);
    delay(5000);// the delay is 5 seconds, it has to wait 5 seconds before it executes the code from the start.
}