Picture protection on my webpage! Help! People keep stealing my pics!?

Question

How can I make it so that on my myspace page when someone right clicks on my photo it gives them a message of my choice about trying to steal my pictures? I know it's possible. I've seen it done. My sister in law and other people keep taking pictures off my myspace page and putting them on their own like they have taken them! It's buggin me. Please help! I don't want them to be able to right click and have the option to Save picture as!