How to install Windows 8 on Mac?
It's not clear if you are looking to evaluate things or make a permanent move, but there is a free solution to evaluate the software as long as you meet the terms for an evaluation license from Microsoft.


Get VirtualBox and run it to make a default Windows 8 container
Register for or log in to your Windows Live account
Download a 32-bit copy of Windows 8 to your Mac
Set that Windows ISO disk image file as the file in the "Optical disk" of the virtual machine by using the Virtual Media Manager window (Command-D)





Start up the Windows 8 container (it will confirm you are using the "Optical disk" to start the machine
Progress through the agreements and start buttons until this screen:





Do not choose the default Upgrade since you have nothing on this "new PC". Choose Custom: Install Windows only (advanced)
Choose the rest of the settings as you please for making your account tied into the Windows Live email and you should be up and running within 10 minutes and a couple reboots of the software "PC".


Other than learning how VirtualBox allocates the keyboard and mouse, you should have 90 days to experiment with the new Windows OS and decide if you want to dive in with BootCamp or a commercial VM solution such as VMWare Fusion or Parallels.