This is not the right place to start learning PCB designing

Why not?! Prahlad did not make any mistake in posting his questions here. May be, they were a bit too demanding...
But if this comes from his eagerness to learn and to solve problems, then I have no problem with it.

By the way, as long as there are still some countries, where fabricating a four layer board means to spend much more than a month's salary, it's worth to discuss, how the optimum performance can be taken from a double sided PCB. Not all people are living in the USA...

Also, it seems to me, that there's a big discrepancy. Many people tell, that they never had used even a double sided PCB with their microcontroller applications, only one sided ones. Others tell that they only use four layer boards. What's right, then? I think, double sided PCB with solid ground plane can cover a very wide range of applications. And it's not at all old fashioned to use them!!

And, what kind of pills shall an engineer take, whose product didn't pass the CE testings, allthough having had used a four layer board?

Kai