During the boot of the system you shoule see a msg that
indicates to press a key that will enter the CMOS or
Setup. Often the key is "DEL" or "F2". The msg will only
display for a short period. If your running a Compaq
computer after the word Compaq displays the cursor will
just to the upper right corner having started in the
upper left corner. While the cursor is in the upper right
corner, repeatedly tap the "F10" key (DO NOT press and
hold the F10 key, the computer will enter the CMOS. Some
other manufactures may have other keys. Gateway for
example, you have to press the TAB key to be able to see
the real msg to enter teh CMOS.
Once in the CMOS or Setup, navagate the menus looking for
an option titled similar to "BOOT ORDER". Once there you
will see the boot order of the system. Look at the screen
and see how to change to boot order. Often times the
arrow keys and page up/down will be used. You will want
the CD drive to be before the hard drive. After making
your changes select save and exit.
Depending on how old the system is booting from the CD
will require a boot disk (floppy) that boots with the CD
drives drivers. You can then run install from there.