ASTERISK Installation & configuration on centos -- Help Needed

Hi All,
MySelf Ponnam, Am planning to use asterisk for internal calls and outbound calls. am new to this asterisk server, could you please guide me in right direction to setup the same by providing installation / configuration documents.

Best regards,

You can googling and find many docs for that!!!

I didn’t found proper document to understand what modules to install first. If you have any links plz forward to me.

Thanks in Advance

For starting:

Thank You very much for the link