Basic Arduino sketch demonstrating analog output with a fade stepping LED.

analog_fade.ino

int ledPin=9; //Store LED pin number in this variable

void setup() {
  //No need for setup this time
  pinMode(ledPin,OUTPUT); //Setup pin 9 for OUTPUT
}

void loop() {
  analogWrite(ledPin,0); //Turn the LED on pin 9 off
  delay(500); //Wait 500 milliseconds
  analogWrite(ledPin,63); //Turn the LED on pin 9 25% on
  delay(500); //Wait 500 milliseconds
  analogWrite(ledPin,126); //Turn the LED on pin 9 50% on
  delay(500);
  analogWrite(ledPin,189); //Turn the LED on pin 9 75% on
  delay(500);
  analogWrite(ledPin,255); //Turn the LED on pin 9 100% on
  delay(500);
}