I have installed Debian for the first time and trying to get freeradius up and running but I am not sure how. I am not so good with Linux and confused by all the documentation and not sure which is applicable to me.

Why am I using Linux then? Because I was told to use it.

Let me give you some background information on what I will be using this for:

I am working for a small ISP that wants to develop a metered internet system.
Customers will have limited accounts (20hrs, 50 hrs etc).
We want the customers to dial up to the radius server and keep track of their hours.

How can I use Debian to implement something like this?