how to instal OS on laptop?

You should give us more information, friend. Are you sure the Hard Drive is correctly inserted? Is your OS laptop-compatible, and does it match the system configuartions? Some older laptops, can't handle big hard drives. first I would suggest you to re-insert the hard drive. And if you use as OS System Windows XP, it should give no problem. When it's Linux, it shouldn't show problems as well. BUT Vista, can actually show some problems, because many hardware isn't really compatible with it. So you should make sure of those things first. You can find the most information, by googling your Laptop. good Luck! And I'm here if you want more help! Success!

Hello, it is helpfull if you did include what kind of OS (Win XP or Vista) you are about to install. I experienced having trouble installing an OS(XP) on a laptop with pre installed Vista. My XP installer doesn't support SATA HD that cause error on my installation.