Getting started with Arduino by flashing the built in LED.

Arduino Blinky Example.ino

#define BUILTIN_LED                     13
#define DELAY_TIME_IN_MILLISECONDS      1000
void setup() {
  pinMode(BUILTIN_LED, OUTPUT);
  digitalWrite(BUILTIN_LED, LOW);
}
void loop() {
  turnLedOn();
  delay(DELAY_TIME_IN_MILLISECONDS);
  turnLedOff();
  delay(DELAY_TIME_IN_MILLISECONDS);
}
void turnLedOn() {
  digitalWrite(BUILTIN_LED, HIGH);
}
void turnLedOff() {
  digitalWrite(BUILTIN_LED, LOW);
}