Here is ahead start on the .htaccess stuff.

You need to be able to open .htaccess to edit and place
RewriteEngine on
RewriteCond %{HTTP_HOST} ^domain\.com$ [NC]
RewriteRule ^(.*)$ http://www.domain.com/$1 [R=301,L]

Replace domain with whatever your domain is and save. If you do this adjustment no body can go domain.com anymore because this is a redirect to www.domain.com. It also stops the search engines from thinking that you have duplicate content.