Setup VirtualHost on Nginx

vim /etc/nginx/conf.d/virutal.conf
server {
 listen 80;
  server_name my-helper.com;
  rewrite ^/(.*) http://www.my-helper.com/$1 permanent;
}

server {
  listen 80;
  server_name www.my-helper.com;
  access_log /var/www/vhosts/my-helper.com/logs/access.log;
   error_log /var/www/vhosts/my-helper.com/logs/error.log;
 location / {
        root    /var/www/vhosts/my-helper.com/htdocs/;
      index   index.php;
  }
}

Reference:
http://articles.slicehost.com/2009/2/25/centos-nginx-virtual-hosts