How do I get an image to fullscreen?

I have attached this to my main camera but I am still not getting full screen.
public class DooDoo : MonoBehaviour {

public Texture backgroundTexture;

void onGUI(){
	GUI.DrawTexture (new Rect (0, 0, Screen.width, Screen.height), backgroundTexture);
	}

}

Adding ScaleMode in your code in function GUI.DrawTexture():

 public Texture backgroundTexture;

 void onGUI(){
  GUI.DrawTexture (new Rect (0, 0, Screen.width, Screen.height), backgroundTexture, ScaleMode.StretchToFill);
 }

Heads up it’s OnGUI() not onGUI(). Note the capital “O”.