Just go into the BIOS -- it's usually invoked by pressing the Del key as the machine first boots (though watch the screen). If I don't know the correct key to press I just press lots of keys at boot-up and this provokes a keyboard error message which usually mentions which key to press for the BIOS.
Once in the BIOS go to Boot Order and put the DVD/CD drive as first, followed by the hard drive.
This is fairly easy all you have to do is start the computer and immediatly press the f2 key this will bring you to the bios menuethen taqb over to the boot screen then you will see the way it is set up now simply scroll down to the cd rom and press the f5 or the f6 key the f5 brings it down while the f6 will move it up once it is at the top of the devices simply press the f10 key to save and exit now once you have your cd rom in the drive restart the computer and it will now boot from the cd rom ok
Hope this helps
Best regards Mike (firstname.lastname@example.org)