question about FDTD simulation

Hi
I am an undergrad student of EMT. I want to learn FDTD. From where should i start? I have different standard books on FDTD such as Teflov etc but these are not for beginners. I have also downloaded "how to program fdtd" but couldn't follow. I just want to start from source free lossless case of Maxwell Eqs. After having discretization of these equations. I want to write a code of them. Is there any body who can help with simple few lines code with stepwise instruction that how the fields are initialized and how these equations will be updated? Thanking in anticipation

Have a look at

https://www.edaboard.com/thread139831.html

and the corresponding wiki at

http://fdtd.wikispaces.com/