I'm interested in web development and by that I mean the bigger projects like facebook or twitter. I know the basics of java, css, php and mysql. I know there is a lot more out there. I read about it. But I don't know what the purpose is and how to put in place.

Things like: Scribe, thrift, casandra, Unix/Linux, shell/perl/python scripting, PostgreSQL, MongoDB, non-relational NoSQL datastores, JVM, nginx 

I want to know why they need it, how they use it and what te purpose is.

What I need is a book like technical background of facebook for dummies or so. 
Are there any books or websites that explain this from scratch?

Thank you!

EDIT:

Thank you for your answers! You have been very helpful. I was in the assumption, experienced programmers know almost anything about the technology there's used today. But as I read, you can only know so much and I need to figure out which technology to use. I take on the encouragement to start building small. And will take on php and improve my skills from there.

Thanks again!