// The pin for the LED id defined.
int ledPin = 8; // Assuming pin 8 was connected to LED.

void setup() {
  pinMode (ledPin, OUTPUT); // The LED pin was set as an output.
}

void loop() {
  digitalWrite (ledPin, HIGH); // The LED was turned on.
  delay (1000); //1 second = 1000 milliseconds
  digitalWrite (ledPin, LOW); // The LED was turned off.
  delay (1000); //1 second = 1000 milliseconds 
}