When installing from the new CD, you may first need to create a bootable installation diskette. IMPORTANT: use a NEW, freshly MS-DOS formatted diskette! Using an old, worn-out, faulty diskette can result in strange problems during the installation!
On a Linux system, you can create the diskette using the dd command:
dd if=/mnt/cdrom/images/boot.img of=/dev/fd0 bs=1440k
On a system running DOS or Windows-9x, you need to use the RAWRITE.EXE program, which is found on the CD in the dosutils directory.
Shut down the machine you want to install (or do a system upgrade) on, insert the boot diskette and your freshly burned CD, and let the machine boot from the diskette. For more information on the installation process, se the documents and the Installation-HOWTO or the Bootdisk-HOWTO which are on the CD in the doc/HOWTO directory.
Most modern machines are able to boot directly from a CD, provided it is made bootable with the procedure outlined in section Creating a bootable CD. Often, however, you need to change the setting of the BIOS to make the CD drive bootable. See the documentation for your mother board to see how it's done.