How to blink a LED on Arduino Board. ;-)

Open Arduino IDE. Select File > New and you’ll be
asked to choose a sketch folder name: this is where your Arduino sketch
will be stored. Name it Blinking_LED and click OK. Then, type the following
text (Example 01) into the Arduino sketch editor (the main window of
the Arduino IDE). You can also download it from www.makezine.com/
getstartedarduino. It should appear as shown in Figure 4-3.

// Example 01 : Blinking LED const int LED = 13; // LED connected to // digital pin 13 void setup() { pinMode(LED, OUTPUT); // sets the digital // pin as output } void loop() { digitalWrite(LED, HIGH); // turns the LED on delay(1000); // waits for a second digitalWrite(LED, LOW); // turns the LED off delay(1000); // waits for a second