Having a working install of Ubuntu 13.04, proceed with the below;

1. Update and upgrade Ubuntu

$ sudo apt-get update
$ sudo apt-get upgrade

2. Install Nginx

$ sudo apt-get install nginx
$ sudo /etc/init.d/nginx start

Nginx should be working now. Try access the server from a browser.

3. Install PHP-FPM

PHP-FPM is a daemon process (with the init script /etc/init.d/php5-fpm) that runs a FastCGI server on the socket /var/run/php5-fpm.sock.

$ sudo apt-get install php5-fpm

Now create the following PHP file in the document root /usr/share/nginx/www

$ vim /usr/share/nginx/www/info.php
// Enclosed in PHP tags of course

Ps: See link 1 below for more detail & some other extra stuff you could do.

  1. Installing Nginx With PHP5 (And PHP-FPM) And MySQL Support (LEMP) On Ubuntu 12.10