Redirection of Non www to www URL

Hello,

My site URL is running without www like "abc.com", I want to add www in my site url like "www.abc.com". Please let me know how to do that.

Thanks

Edit ./inc/header.inc.php and edit the site URL to include www.  Save and clear Dolphin's cache.  To manually clear the cache, empty the ./cache ./cache_public, and ./tmp directories, except for the .htaccess files inside them.

You'd better 301 redirect requests for non-www version to WWW as well if your site is currently live and has been indexed with non-www URLs.

 he also have to do that step nathon told, otherwise it will create a redirect loop.

Yes, that's who I said "as well". 

 cool :P