int Red = 12;
int Yellow = 7;
int Green = 2;

void setup() {
  // put your setup code here, to run once:
  pinMode(Red, OUTPUT);
  pinMode(Yellow, OUTPUT);
  pinMode(Green, OUTPUT);
}

void loop() {
  // put your main code here, to run repeatedly:
  digitalWrite(Red, HIGH);
  delay(6000);
  digitalWrite(Red, LOW);
  digitalWrite(Yellow, HIGH);
  delay(4000);
  digitalWrite(Yellow, LOW);
  digitalWrite(Green, HIGH);
  delay(2000);
  digitalWrite(Green, LOW);
}