www in domain not working in nginx

I'm new to using nginx, well, new to using anything that's not cpanel... I'm having problems getting domains to work using nginx when you include www. in the url.

www.mydomain.com > not work 404
mydomain.com > works

I'm not sure if I have made mistake with named config files, or the server config for nginx. I'm kinda learning in a hurry and I'm not going to be surprised if I made some error with basic configuration. I run latest nginx & php-fpm, apart from my domain issue it works.

I'm (trying?) to run subdomains, they work, but using www. will result in a 404. I use nameservers etc from my main .org server domain. I'm going to post all that is relevant below in the hope someone here can spot the errors I am making/or made.

etc/hosts 
# Do not remove the following line, or various programs
# that require network functionality will fail.
127.0.0.1       localhost.localdomain localhost
::1             localhost6.localdomain6 localhost6
184.xxx.xxx.146 server.servername.org servername.org 

named.conf

   ... 
   view "localhost_resolver" {
/* This view sets up named to be a localhost resolver ( caching only nameserver ).
 * If all you want is a caching-only nameserver, then you need only define this view:
 */
   # match-clients         { 127.0.0.0/24; };
   # match-destinations    { localhost; };
   match-clients      { any; };
   match-destinations { any; };
   recursion no;

        zone "servername.org" {
                type master;
                file "/var/named/servername.org.db";
        };

// optional - we act as the slave (secondary) for the delegated domain
zone "mydomain.com" IN {
  type slave;
  file "/var/named/mydomain.com.db";
  masters {10.10.0.24;};
}; 
allow-notify { 184.xxx.xxx.146; };
};

mydomain.com.db

$TTL    86400
mydomain.com.  IN      SOA     ns1.servername.org.      server.servername.org.