int TASTER = 13;
int TasterLesen;
int LED = 7;

void setup()
{
  pinMode(LED, OUTPUT);
  pinMode(TASTER, INPUT_PULLUP);
}

void loop()
{
  // Tasterstatus lesen
  TasterLesen = digitalRead(TASTER);

  // Taster gedrueckt
  if (TasterLesen == LOW) 
  {
    digitalWrite(LED, HIGH);
  }
  
  // sonst 
  else
  {
    digitalWrite(LED, LOW);
  }
}