The installation of FreeNAS is very simple and only a few configurations have to be done.
Installation of FreeNAS
Download the FreeNAS ISO and install it on your server: http://www.freenas.org/download-freenas-release/
The installation of freenas operating system is simple, you just need to follow the instructions in the installation wizard.
Configuration of FreeNAS
Follow these pages to configurate FreeNAS. Make the configuration in the same order as listed here.