const int buttonPin = 2;    //dig.pin connect to switch
const int ledPin = 13;     //pin connected to led
int buttonState = 0;       //initial value of switch

void setup() {
  // put your setup code here, to run once:
  pinMode(ledPin, OUTPUT);    //set led pin as output
  pinMode(buttonPin, INPUT);  //set switch pin as input
}

void loop() {
  // put your main code here, to run repeatedly:
  buttonState = digitalRead(buttonPin);  //read input from pin 2
  if (buttonState == HIGH) {            //if switch pressed, set as HIGH
    digitalWrite(ledPin, HIGH);  //turn ON led
  }
  else {
    digitalWrite(ledPin, LOW);  //otherwise, OFF led
  }
}