My "first" Arduino sketch

sketch_jan30a.ino

int switchState = 0;
int lightOn = 0;
int led = 13;

void setup() {
  pinMode(3, OUTPUT);
  pinMode(4, OUTPUT);
  pinMode(5, OUTPUT);
  pinMode(2, INPUT);
  pinMode(led, OUTPUT);     
}

void loop() {
  switchState = digitalRead(2);
  if (switchState == LOW) {
    digitalWrite(3, HIGH);
    digitalWrite(4, LOW);
    digitalWrite(5, LOW);
    digitalWrite(led, LOW);
  }
  else {
    lightOn++;
    if (lightOn > 2) {
      lightOn = 0;
    }
    digitalWrite(3, LOW);
    digitalWrite(4, LOW);
    digitalWrite(5, LOW);
    digitalWrite(led, LOW);
    switch (lightOn) {
      case 0:
        digitalWrite(4, HIGH);
        break;
      case 1:
        digitalWrite(5, HIGH);
        break;
      case 2:
        digitalWrite(led, HIGH);
        break;
    }
    delay(150);
  }
}