This information is all in your includes/configure.php files and admin/includes/configure.php file

The key information that needs to contain www.yoursite.com is
Code:
// Define the webserver and path parameters
// HTTP_SERVER is your Main webserver: eg, http://www.yourdomain.com
// HTTPS_SERVER is your Secure webserver: eg, https://www.yourdomain.com
  define('HTTP_SERVER', 'http://www.yoursite.com');
  define('HTTPS_SERVER', 'https://www.yoursite.com');
You are probably missing the "www" in those files, since all the links are generated from this information.