int potpin = 0;  // analog pin used to connect the potentiometer
int val;    // variable to read the value from the analog pin

void setup() {
  pinMode(10,OUTPUT);  // attaches the servo on pin 9 to the servo object

}

void loop() {
  val = analogRead(potpin); 
  val = map(val,0,1023,0,255);           // reads the value of the potentiometer (value between 0 and 1023)
  analogWrite(10,val);    
}