In most computers the first booting device set is the HD0 or your hard disk where your Operating System is installed or in older PC’s the floppy drive is the first booting device.  To set CD ROM as the first booting device follow the basic steps:

  1. Restart your if its is turned on, if not start up your compute
  2. watch carefully for the message on how to enter your Bios settings (like pressing F2 or the Del key), and you should press the correct key.  The message usually is the first message displayed on the lower part of the screen.
  3. When you are on the Bios settings, find the boot sequence option.  Go into it(usually press the enter button but there are directions bellow or on the side) and select the CD Drive as the first bootable option.                                                                                                                                                                                                                                                                                                   CAUTION: False move or wrong changes inside your bios  can seriously affect your computer‘s operation.  Take extra careful and make sure you only edit the boot sequence settings.
  4. You should save the settings for the changes to take effect.  This usually done by pressing F10 and press Y(for Yes) to save the changes.
  5. .
  6. Insert your bootable CD so that you can enter the User Interface for the CD booted.

Here is a view of the images.

boot-sequence