Multiplexing Help - Digital I/O Pins

Using Arduino LEDs and Multiplexing
3

#define PIN10 10

void setup() {

pinMode(PIN10 , OUTPUT); // set PIN10 as output
}

void loop() {
digitalWrite(PIN10 , HIGH); // turn PIN 10 on
delay(1000); // wait for a second
digitalWrite(PIN10 , LOW); // turnPIN 10 off
delay(1000); // wait for a second
}