I need assistance with a project.

Using Arduino Project Guidance
10

The reason i'm doing this in the first place is because there is NO lamp in my trunk. Instead of installing a plain light, I wanted to make an aesthetically pleasing LED arrangement to complement my subs. This is where I am. I think this should be working. I've got the LED hooked up to the GND and 13. I have a mommentary push button hooked up one end on the 5 volt spot, and the other on the #2 spot. This is what the code looks like.

const int buttonPin = 2;     
const int ledPin =  13;      


int buttonState = 0;        

void setup() {
  pinMode(ledPin, OUTPUT);      
  pinMode(buttonPin, INPUT);     
}

void loop(){
  buttonState = digitalRead(buttonPin);
  if (buttonState == HIGH) {        
    digitalWrite(ledPin, HIGH);  
  } 
  else {
    digitalWrite(ledPin, LOW); 
  }
}

It's really unpredictable now. It will work sometimes, and others it flicker or stay on and the button won't turn it off. Should the button be grounded? What's going on?