int button1=3;
int ledGw=4;
int button2=0;
void setup() {
  pinMode(ledGw, OUTPUT);
  pinMode(button1, INPUT);
}

void loop() {
  button2=digitalRead(button1);
  if (button2==HIGH)
  {
    digitalWrite(ledGw, HIGH);
  }
  else
  {
    digitalWrite(ledGw, LOW);
  }
}