int redPin = 2;
int greenPin = 3;
int bluePin = 4;

void setup() {
  pinMode(redPin, OUTPUT);
  pinMode(greenPin, OUTPUT);
  pinMode(bluePin, OUTPUT);
}

void loop() {
    analogWrite(redPin, 255);
    delay(100);
    analogWrite(greenPin, 255);
       delay(100);
    analogWrite(redPin, 255-1);
       delay(100);
    analogWrite(greenPin, 255);
       delay(100);
    analogWrite(bluePin, 255); 
       delay(100); 
    analogWrite(greenPin, 255-1);
       delay(100);
    analogWrite(bluePin, 255);
       delay(100);
    analogWrite(redPin, 255);
       delay(100);
    analogWrite(bluePin, 255-1);
       delay(100);
    }