int switchPin = 3;
int ledPin= 8;
boolean lastButton = LOW;
boolean currentButton = LOW;
int ledLevel = 0;

void setup() 
{
  pinMode(switchPin, INPUT);
  pinMode(ledPin, OUTPUT);
}

boolean debounce(boolean last)
{
  boolean current = digitalRead(switchPin);
  if (last != current)
  {
    delay(5);
    current = digitalRead(switchPin);
  }
  return current;
}

void loop() 
{
  currentButton = debounce(lastButton);
  if (lastButton == LOW && currentButton == HIGH)
  {
    ledLevel = ledLevel + 51;
  }
    lastButton = currentButton;

    if (ledLevel > 255) ledLevel = 0;
    analogWrite(ledPin, ledLevel);
}