int LED = 18;
int PUSH = 15;
int PushState = 0;

void setup()
{
  pinMode(PUSH, INPUT);
  pinMode(LED, OUTPUT);
}

void loop()
{
  PushState = digitalRead(PUSH);
  if (PushState == HIGH) {
    digitalWrite(LED,HIGH);
  } else{
    digitalWrite(LED,LOW);
  }
}