I just read a book about JavaScripting and this is what I wrote without help. But I failed, can anyone correct me and tell me why it’s wrong? Please & Thank you! From: JavaScript NOOB 
var Play : GUITexture;
var Exit : GUITexture;
function Play(){
if(Input.GetMouseButtonDown);
Application.LoadLevel.("Level-1");
function Exit(){
if(Input.GetMouseButton);
Application.Quit();
}
}
You haven’t specified what mouse button to use. Look up GetMouseButton and GetMouseButtonDown in the documentation. Also, you have an extraneous “.” after LoadLevel, you’re using “;” after if statements (you only use “;” at the end of lines), and your braces are all mismatched. (Also, not that it’s a syntax error, but you should use lowercase for variable names; uppercase is for functions and classes.)
Take a look at this
function OnGUI () {
// Make a background box
GUI.Box (Rect (10,10,100,90), "Loader Menu");
// Make the first button. If it is pressed, Application.Loadlevel (1) will be executed
if (GUI.Button (Rect (20,40,80,20), "Level 1")) {
Application.LoadLevel (1);
}
// Make the second button.
if (GUI.Button (Rect (20,70,80,20), "Level 2")) {
Application.LoadLevel (2);
}
}
Customize it to your needs ^^