What is "BIOS boot order"? When you turn on your computer it will look for any operating system to load up. Once it finds an operating system, it's done looking, and the operating system takes over. The Windows operating system is located on the hard drive inside the computer. But a computer can also look elsewhere for an operating system, such as to a CD-ROM drive. An Ubuntu boot CD contains its own operating system (that is independent of Windows). In order for a computer to boot up with the Ubuntu operating system found on the CD, the BIOS boot order must be configured to "check" the CD-ROM drive before it looks on the hard drive, otherwise the computer will just continue to load Windows.

By default most but not all computers are set to "look" for an operating system in the CD-ROM drive first. If it happens to find a CD with an operating system it may ask you to "press any key to boot from CD". Otherwise it just proceeds to the 2nd option, which is usually to look on the hard drive for an operating system.

If you correctly created an Ubuntu boot CD, placed it in the CD drive, and started up your computer but the Ubuntu operating system never loaded up, chances are that the CD-ROM drive is not first in line in the BIOS boot order.  In this case you'll need to change the BIOS boot order.

How? On most (but not all) computers, when you first turn on your computer, you will have to continually press the "F2" key or the "delete" key over and over (about once or twice per second) until the BIOS appears. If "F2" or "delete" don't get you to the BIOS screen then visit THIS PAGE for help. Once you get to the BIOS screen, use the right, left, up, or down arrow keys to navigate to the "boot" tab. Then use those same arrow keys to select the CD-ROM drive. Once selected you can use the + or - keys to move CD-ROM to a higher boot order.

Once you change the BIOS boot order, on most computers you can press the "Esc" key to exit the boot order menu, and then press "Esc" again to exit the BIOS so that you can retry booting with the Ubuntu CD. Be sure the SAVE the BIOS changes you made. How? This is usually the last screen that appears as you are pressing "Esc" to exit the BIOS. Usually you use the left, right, up, or down arrow keys to highlight "Save and exit", then press the "Enter" key.

THIS PAGE has a nice explanation about how to change a BIOS boot order

THIS PAGE also has instructions on how to enter the BIOS, in case neither the "F2" key or the "delete" key cause the BIOS screen to appear.