void setup() {
  pinMode(8, OUTPUT); //pin 8 is connected to Red LED
  pinMode(9, OUTPUT); //pin 9 is connected to Yellow LED
  pinMode(10, OUTPUT); //pin 10 is connected to Green LED
  pinMode(11, OUTPUT); //pin 11 is connected to Red LED
  pinMode(12, OUTPUT); //pin 12 is connected to Yellow LED
  pinMode(13, OUTPUT); //pin 13 is connected to Green LED

}

void loop() {
 digitalWrite(8, HIGH);
 delay(3000);
 digitalWrite(8, LOW);
 digitalWrite(9, HIGH);
 delay(2000);
 digitalWrite(9, LOW);
 digitalWrite(10, HIGH);
 delay(3000);
 digitalWrite(10, LOW);
 digitalWrite(11, HIGH);
 delay(3000);
 digitalWrite(11, LOW);
 digitalWrite(12, HIGH);
 delay(2000);
 digitalWrite(12, LOW);
 digitalWrite(13, HIGH);
 delay(3000);
 digitalWrite(13, LOW);
}