Search engines makes the difference between domain with www and without it so that is the reason why you have such results.
I guess that you didn't even bother to search what "redirect the www from the .htaccess on my server" means and how to solve this so here it is:
lmgtfy.com/?q=Redirecting+non-www+to+www+with+.htaccess
Basically you have to add the following to your .htaccess file:
RewriteEngine On
RewriteCond %{HTTP_HOST} !^www\.
RewriteRule ^(.*)$ http://www.%{HTTP_HOST}/$1 [R=301,L]