int cnt=0;
void setup() {
  DDRB= 0xFF; //setting as output pin
}

void loop() {
  PORTB |= (1<<cnt); //setting the required pin as 1 to glow
  delay(100);
  PORTB &= ~(1<<cnt); //resetting the pin
  delay(100);
  cnt++;
  if(cnt>7)
  cnt=0;
}