The above links tell you how to reset your PC to the state when you bought it, which is why I posted them. Have you looked at them?
If you're unable to follow the instructions there, I can only suggest you ask a techy friend to help.
Most people who sell such netbooks etc follow this before the sell them on ebay, for example.
Saving your data means, in the simplest terms, copying it from your PC to another device attached to you r PC in some manner, whether that be over a LAN, to a separate disk via a USB connection, or to some online storage by internet.