#define potV A2 
#define LED 3        

void setup() {
  pinMode(potV, INPUT);
  pinMode(LED, OUTPUT);
  digitalWrite(LED, LOW);          
}

void loop() {
  int analogIn =0, pwm;
    analogIn = analogRead(potV);  

  pwm = map(analogIn, 0, 1023, 0, 255);
  analogWrite(LED, pwm);
}