If you have to ask questions such as these you're better off simply letting Windows manage itself. The registry is no place for amateurs, you can easily render your OS unbootable and unfixable with the wrong edit.
For the moment lets assume I am not an amateur and possibly trainable. I have used regedit successfully in the past. I have made mistakes and fixed them. So, my question remains the same. Is there a guide our detailed article describing regedit and the best way to use it.