Hi,
insert the installation CD and then restart the computer.
press any key when you will be prompted to do so.
the installation will begin.
follow the wizard and press F8 when you will be prompted for the Windows agreement.
then the setup will search for existing windows, press enter.
then you need to follow the wizards and they will guide you through the installation.
note that installing windows will erase all the data contained in the hard disk.