Disable right mouse click Script

I need a Disable right mouse click Script because i do not want tat somebody will copy so easy my pages. I know that it’s impossible to 100% secure my content but i want to keep some here.
My pages are now like this:
http://www.letras32.com/letras/s.php
or artist pages:

http://www.letras32.com/es/top100artists.php
http://www.letras32.com/es/top100letras.php

I want this script to be free and to be easy to understand in case that i want to change something.

Many thaks,
Adam Sam