How Can A Time Machine Be Built?

I haven't really seen anything that tells you how you can build a time machine, but there have been many people saying how it might be possible.  I have tried to understand this from the literature and books I've read, and the closest I've come to something that a lay person can understand is probably the book by Paul Davies called 'How to Build a Time Machine', and also he has an article in the Scientific American
www.sciam.com

I would highly recommend getting some basic quantum physics behind you before you tackle any of the serious literature and understand it, but these should give you a good starting point.