The default web address http://sites.google.com/site/nraveen for this site is quite long and not easy to remember. Hence I added a simple address www.raveen.net to point to this site.
1) I bought a domain name (http://raveen.net), changed CNAME alias as www.raveen.net and destination as ghs.googlehosted.com.
2) In the Google sites settings, added a web address as www.raveen.net.
It took few hours for DNS propagation and working successfully. Now this site can be reached using the simple address www.raveen.net.