How do I re-boot my computer to start over fresh every site I go to wants me to buy something.I just want to do it the easy way myself.

You really need to start your own question,

Go to this link and click, Ask About Windows, this will start your own question and try to provide as much info about your question - the how's and why's, model PC cersion of windows, etc..
Windows - Ask Me Help Desk

I've moved your questions ot its own thread.

I don't understand what sites wanting you to buy something has to do with it.

If talking about XP

How to Format Drive and Install Windows XP from Scratch

Geek to Live: How to format your hard drive and install Windows XP from scratch


Installing Windows Vista
Installing Windows Vista - NeoSmart Technologies Wiki