Level 1

Heading 1

void setup() {
  pinMode(LED_BUILTIN, OUTPUT);
}

void loop() {
  digitalWrite(LED_BUILTIN, HIGH);
  delay(1000);
  digitalWrite(LED_BUILTIN, LOW);
  delay(1000);
}

Heading 2

int led_one = 2;
int led_two = 3;
int led_three = 4;

void setup() {
  pinMode(led_one, OUTPUT);
  pinMode(led_two, OUTPUT);
  pinMode(led_two, OUTPUT);
}

void loop() {
  digitalWrite(led_one, HIGH);
  delay(7000);
  digitalWrite(led_one, LOW);
  digitalWrite(led_two, HIGH);
  delay(3000);
  digitalWrite(led_two, LOW);
  digitalWrite(led_three, HIGH);
  delay(10000);
  digitalWrite(led_three, LOW);
}

Heading 3

int redPin= 3;
int greenPin = 5;
int  bluePin = 6;

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

void  loop() {
  setColor(255, 0, 0); // Red Color
  delay(1000);
  setColor(0,  255, 0); // Green Color
  delay(1000);
  setColor(0, 0, 255); // Blue Color
  delay(1000);
  setColor(255, 255, 255); // White Color
  delay(1000);
  setColor(170, 0, 255); // Purple Color
  delay(1000);
  setColor(127, 127,  127); // Light Blue
  delay(1000);
}

void setColor(int redValue, int greenValue,  int blueValue) {
  analogWrite(redPin, redValue);
  analogWrite(greenPin,  greenValue);
  analogWrite(bluePin, blueValue);
}