int pirPin = 2;
int relayPin = 7;
int motion;

void setup() {
  pinMode(pirPin, INPUT);
  pinMode(relayPin, OUTPUT);
  Serial.begin(9600);
}

void loop() {
 motion = digitalRead(pirPin);

  if(motion == HIGH) {
    digitalWrite(relayPin, HIGH);
    Serial.println("motion detected - Relay on");
  }
  else {
    digitalWrite(relayPin, LOW);
    Serial.println("NO motion - Relay off");
  }
  delay(100);
}