int LDR_Pin = A0; //analog pin 0
int Led_Pin = 13; //analog pin 0

void setup(){
  Serial.begin(9600);
  pinMode(LDR_Pin, OUTPUT);
  pinMode(Led_Pin, OUTPUT);
}

void loop(){
  int LDRReading = analogRead(LDR_Pin); 

  Serial.println(LDRReading);
  if (LDRReading>100) {digitalWrite(Led_Pin, HIGH);};
  if (LDRReading<100) {digitalWrite(Led_Pin, LOW);};
  delay(250); //just here to slow down the output for easier reading
}