Go into the bios on start up (alt+control+ delete) buttons all down together
find the boot section and turn on boot from cd
allow all cd units and it will find a cd ( external hard drive ) and boot up
take it to a computer shop and have them set it up
or

If your computer is working and you want an external hard drive to save to-- open the computer and with the external hard drive switched off, plug in the usb cables. turn on the hard drive and the computer will recognize it as a plug in unit and search for the correct driver
it may ask for a disc for installation or search on line ( use the disc in the cd drive in the computer)
from there the wizard will install the external hard drive