What makes you think you can improve performance that way? If it were that simple Microsoft would have built it that way. Most registry tweaks do not involve performance, and those that do normally address a certain problem that you may or may not experience depending on your exact environment and will hurt performance if you don't have the problem. I don't know of a single thing that you can do that will automatically increase performance no matter what. So my advice is to leave it alone. As far as learning it is concerned, I think it's too big to learn, but here is a link to an article on the basics of it.
http://www.geekgirls.com/windows_registry01.htm