Need help how to install beta5 on- new computer

hi need help : i Download the AsteriskNOW ISO file, and create a CD image from the file, i Insert the newly created AsteriskNOW CD into the CD-ROM drive of the PC and Boot from the CD by restarting the PC.
the AsteriskNOW boot menu Didn’t show and i get a bios Message “insert system disk and reboot” .
do i need to install linux first??? what went wrong???