Hi Bette,
if you could post the make and model of the laptop we could advise you further on which operating system would suit best. It also depends on the age of the machine.
To actually install the operating system you'll need to first enter the laptops Bios. This is done by pressing either F2 or the delete key. Usually it tells you, on screen, when the machine starts up which keys to press to enter set up. Once in the Bios you'll need to change the Boot order. This is so the machine will check first the DVD-Rom (which contain the install DVD)for install information instead of the Hard disk drive (which contains nothing yet). If the laptop has a manual it may even tell you how to enter the bios and indeed where to find the actual settings but again if you post the make and model we'll be able to tell you more.
Once the boot order has been changed the you simply need to save the settings and then reboot making sure the disk is in the drive. Watch for onscreen prompts as you'll need to press any key to start the install process so don't miss it.
Once you know the make and model post back.