int switchState = 0;

void setup(){

 pinMode(3,OUTPUT);
 pinMode(4,OUTPUT);
 pinMode(5,OUTPUT);
 pinMode(2,INPUT);
}
void loop(){
 switchState = digitalRead(2);
 if (switchState == LOW) { 
 // the buton is not pressed
 digitalWrite(3, HIGH); // green LED
 digitalWrite(4, LOW); // red LED
 digitalWrite(5, LOW); // red LED
 } 
 else { // the buton is pressed
 digitalWrite(3, LOW); 
 digitalWrite(4, LOW);
 digitalWrite(5, HIGH);
 delay(250); // wait for a quarter second
 // toggle the LEDs
 digitalWrite(4, HIGH); 
 digitalWrite(5, LOW);
 delay(250); // wait for a quarter second
 } 
} // go back to the beginning of the loop

 // this is a comment