New to VoIP. Please help

Please read it. I need your help. Any suggestion is highly appreciated.

I am new to VoIP. Just completed graduation on Electronic & Telecommunication Engineering. I want to start professional life with Asterisk. How do I start it? Which will be the best to start with? Formerly I have much knowledge on PHP, HTML, CSS, jQuery.
I am using windows in my laptop and want to setup asterisk. Is windows better for this? I want to set up call center solution or asterisk system for clients. What is the way to do that?

(All development work on Windows ceased many years ago, and that version ran in a simulated Linux environment (cygwin). If you wnat to work with Asterisk you need to learn Linux.)