That's not exactly an ASP.NET question, but I'll try to answer. First, you have to know that there is no way you can absolutely protect the source of your page. Any determined hacker will be able to get to it no matter what you do. If the browser can access it to render it, anyone can do it.
To disable the right click button, you just need to handle the onmousedown event:
<body onmousedown="if((event.button|2)!=0){alert('Right button disabled');}">