int knopka=2;
int lampa=6;

void setup() {
  // put your setup code here, to run once:
  pinMode(knopka,INPUT);
  pinMode(lampa,OUTPUT);
}

void loop() {
  // put your main code here, to run repeatedly:
  if (digitalRead(knopka) == HIGH) {
    digitalWrite(lampa,HIGH);
  }
  else {
    digitalWrite(lampa,LOW);
  }
}