Download, burn the .ISO file, put DVD in tray, reboot, set up BIOS to boot from DVD.  Press enter to boot. If everythings OK, youll get to GUI.  Choose your language, follow the onscreen instruction, if there are issues with your HD, simply open Disk Utility from the top menu and format your HD to 1 partition GUID and you are now ready to proceed installing on the main drive. Give it 20 to 25 minute and installation is done! Simple reboot  when told.  And enjoy your own Mac World!