#define POTENTIOMETER A0
#define LED 9

int potValue = 0;

void setup() 
{
  pinMode(POTENTIOMETER, INPUT);
  pinMode(LED, OUTPUT);

}

void loop() 
{
  potValue = analogRead(POTENTIOMETER);

  potValue = map(potValue, 0, 1023, 0, 255);

  analogWrite(LED, potValue);

}