Probably the simplest way to redirect the non-www to the www is to put this in your .htaccess file
RewriteEngine On Options +FollowSymLinks
RewriteCond %{HTTP_HOST} ^example.com
RewriteRule (.*) http://www.example.com/$1 [R=301,L]
RewriteCond %{THE_REQUEST} ^./index.html
RewriteRule ^(.)index.html$ http://www.example.com/$1 [R=301,L]
For reference the .htaccess file goes in the root of your domain via whatever file transfer program you use and of course replace example.com with your domain
If you get stuck, let me know