Need Help for Billing system

I am using Asterisk 1.8 and FreePBX 2.9.

I want to add a billing system for Asterisk Server. How I can do that for my system…???
I heard about A2Billing system, but I don’t know how to implement that. How can I install and configure that…???

Please anyone help with details with the installation and configuration for the billing system for Asterisk Server.

you should visit their website star2billing.com/
In the source file it has an installation document .