It's long been without argument that nmap, written by Fyodor, is a cut above the rest when it comes to network scanning. It should therefor be a surprise to nobody that Fyodor's book achieves a similarly high standard in explaining the hows, whys and wherefors of using this tool.
The book starts by giving us a solid grounding in the basics before moving onto standard scanning techniques such as discovery and port scanning. Of course being the book that it is this isn't your 10,000ft view of port scanning one IP address with a choice of three flags, the book goes into the detail you would expect with the sort of information that true afficianadoes lust after.
The book goes on to cover in detail a variety of other topics such as optimisation, service scanning, OS detection, the nmap scripting engine and a bunch of other similarly useful stuff.
In the same way that nmap has always been the answer for port scanning this book is most definitely the answer for your questions on how to get the most out of it. The book is easy and fun to read with great examples along the way.