when you power on the computer hold down the ESC key from the keyboard.
read the instructions of this link , this link will help you to go to the bios mode.
http://michaelstevenstech.com/bios_manufacture r.htm
when you enter into the bios mode make the cd/dvd rom as the first drive and the hard drive as the second drive.
put the cd into the cd rom and start the computer.
installation will start.
for further assistance you can approach at this source at
http://www.iyogi.co.uk/microsoft-operating-sys tem.html