const int switchPin = 2;  
const int motorPin = 9;   

int switchState = 0;  

void setup() {
  //motor pin as an output:
  pinMode(motorPin, OUTPUT);
  //pin as an input:
  pinMode(switchPin, INPUT);
}

void loop() {
  switchState = digitalRead(switchPin);
  if (switchState == HIGH) {
    // turn motor on:
    digitalWrite(motorPin, HIGH);
  } else {
    //motor off
    digitalWrite(motorPin, LOW);
  }
}