How to use Nginx to load balance a website

Have a look at http://mickeyben.com/2009/12/30/using-nginx-as-a-load-balancer.html to see how to use Nginx as a load balancer.

upstream  yoursite  {
   server   yoursite1.yoursite.com;
   server   yoursite2.yoursite.com;
}

server {
   server_name www.yoursite.com;
   location / {
      proxy_pass  http://yoursite;
   }
}

The configuration is really simple, additionally you can use the ip_hash directive to forward all the request of the same client to the same server:

upstream  yoursite  {
   ip_hash;
   server   yoursite1.yoursite.com;
   server   yoursite2.yoursite.com;
}