You need to enter the BIOS, or sometimes known as setup mode. When you boot
your computer up, you will see a message saying (usually) "hit delete to
enter setup". Do just that. This will take you to a blue BIOS setup screen.
Go to "advanced CMOS setup" and you will see a section called Boot order.
This enables you to change the order your computer will look for a boot
record from. It is commonly set up as "Floppy, IDE0. Look for instructions
on the page as to how to change the order. This is commonly using the Page
up/ Page down keys. I usually change it to "CD ROM, Floppy, IDE0". When this
is done, hit escape to take you back to the main BIOS menu, go down to "Save
settings and exit" and hit that. You will then get a prompt saying are you
sure you want to exit and save settings Y/N? Make sure you hit Y and your
computer will then reboot. You should then have it booting from the CD as a
first option. hope this helps....