How to Set BIOS to Boot from CDROM:All modern Computer Systems manufactured in the last years, support boot from cd feature, but it may be required to configure this feature in bios or previous owner of your computer system may have disabled this feature or may have changed the boot priority sequence )
When you start your computer, check the boot-screen for setup key, In most newer pc it will be
DELETE key, so make sure to check it.
This AmiBios Require you to press DEL key to enter setup
now you will see some similar screen and choose the
BOOT option and choose
Boot Device Priority and choose first boot device to
CDROM and second boot device to
HARD DRIVE You can press
F10 to save settings.
On Award Bios you will see some similar screen and choose the right key to
Enter setup
Now choose
Advanced Bios Features
and set
First Boot Device to
CDROM and Second or third to
HDD-0 and Press
F10 to save it.
On some Dell Systems you can enter bios by pressing
F2
Now choose
Boot Sequence and then arrance
1 to CD-Rom by pressing
- + and press
space to enable it
Press
ESC and choose save settings and
exit 
On some
Dell Systems you can enter bios by pressing
F2
Sometimes you can press
F12 to temporary boot from cd on some Dell Systems
Press
F2 to enter bios setup
and set
Boot Sequence to
A,CDROM,
C and Press
Esc and then
F10 to save it.
Some Computer has Option to temporary boot from Cd/Hdd/Floppy/Usb Device, Just keep tapping the
F8 button to get Boot Menu and Now choose your manufacture of CDRom.
You can find more advice and help here:
http://www.briteccomputers.co.uk/forum/tutorials-and-how-to/how-to-accessenter-bios-mode-on-your-pc-or-laptop/source
