Do you need to redirect your traffic from http://yoururl.com to http://www.yoururl.com. If yes, then put below code in your .htaccess file located in the WordPress Root Installation.

RewriteEngine On
RewriteCond %{HTTP_HOST} !^www\.
RewriteRule ^(.*)$ http://www.%{HTTP_HOST}/$1 [R=301,L]

Now, you domain will be start redirecting from non www to www.