I too am a beginner and would echo the sentiments of skirnir. That is, you don't have to master everything in the book. Unless of course your project needs it. Often when there's a concept I can't comprehend or have zero knowledge of I panic and immediately think I need to buy a book, but if I'm patient and keep at it, I'll find something that shows me the way.

If you really want to buy a book and/or browse through it, look at Perl by Example by Ellie Quigley. It does cover much about processes and forks, and PIDs, and much other stuff that I'm interested in but will wait until I need more depth. In fact I've been working through this book and got tired of it so took a diversion through a small project or two, and attempted CPAN testing, and Net::Telnet, and, and, etc. I always know where the information is when I need it.