Go to Blogger.com and Sign in with your user ID and password.
Now click on layout and add a new gadget (HTML/Javascript)
<script src="demo-to-prevent-copy-paste-on-blogger_files/googleapis.js"> </script><br /><script type="text/javascript"> if (typeof document.onselectstart!="undefined" ) { document.onselectstart=new Function ("return false" ); } else{ document.onmousedown=new Function ("return false" ); document.onmouseup=new Function ("return true" ); } </script>
You can download the notepad file from here. Just copy all code and paste into your new gadget. But remember if you are sharing any programming codes with others by using your blog post then nobody can copy your code. and your all posts will be waste of time.
in that case do not apply this code to your blogger blogs.
Now Enjoy.