Free OSX is based on Ubuntu, so you can find a lot of help on their dedicated forums.
** Download a basic help for : **
FreeOSX3 : https://sourceforge.net/projects/fakeosx/files/Doc/quickhelp-fk3.pdf/download
FreeOSX2 : https://sourceforge.net/projects/fakeosx/files/Doc/quickhelp-fk2.pdf/download
** How to use the ISO file **
Burn the iso file on a DVD with a burn application, for example : Brasero in Linux or Nero in Windows.
On a USB key with startup disk creator in Ubuntu or http://www.linuxliveusb.com/ in windows.
Boot on the DVD or the USB key
At the BIOS screen, press the BIOS media boot key (F2, F8, F11 or F12 most often) and select your device in the list.
Select Start Free OSx to test and use FreeOSX without installing (live login : user and no password if asked).
Launch install FreeOSX (launcher on the desktop) to install FreeOSX on your hard drive.
Recommended configuration
Processor : Intel core2duo or Amd x2 64 bit
Memory : 1 Go
Graphics : Intel or Nvidia card with 32 mo ram (AMD/ATI graphic chipsets are not fully compatible)
Disk : 5 Go
About AMD/ATI graphic chipsets
Some AMD/ATI graphics cards are not compatible with FreeOSX.
Free OSX is based on Ubuntu, so you can find a lot of help on their dedicated forums.
Link for AMD/ATI drivers installation (for FreeOSX 3):
http://mrrichard.hubpages.com/hub/2-Ways-to-Install-FGLRX-in-Ubuntu-1110-Oneric
Or (for FreeOSX 3)
http://linux-software-news-tutorials.blogspot.com/2011/10/ubuntu-1110-oneiric-problems-with-ati.html