By far the easiest way to install Ubuntu is from an Official Ubuntu CD-ROM . You may download the CD-ROM image from an Ubuntu mirror and make your own CD, if you have a fast network connection and a CD burner. If you have an Ubuntu CD and CDs are bootable on your machine , you can skip right to Chapter 5, Booting the Installation System; much effort has been expended to ensure the files most people need are there on the CD.
If your machine doesn't support CD booting, but you do have a CD or an ISO image, you can use an alternative strategy such as hard disk, net boot, or manually loading the kernel from the CD to initially boot the system installer. The files you need for booting by another means are also on the CD; the Ubuntu network archive and CD folder organization are identical. So when archive file paths are given below for particular files you need for booting, look for those files in the same directories and subdirectories on your CD.
Once the installer is booted, it will be able to obtain all the other files it needs from the CD.
If you don't have a CD, then you will need to download the installer system files and place them on a hard disk or a connected computer, so they can be used to find and boot the installer.