what you have to do is boot off the discs, put the disc labeled #1 in the cd/dvd tray and reboot the pc. It should boot to it automaticly but if not reboot agian and enter the bios (press f2, enter, delete or f12 depends on the system but it should display what button to press to enter setup).
change the boot order to include the the cd/dvd. after that just follow the prompts and change discs as instructed.