My b2evolution Version: Not Entered

Hello,
I'm new to b2evolution: I installed on my website and played with its configuration. So far it is running fine, but I have a question:

Is it possible to configure b2evolution to create a private blog where only selected group of people can read its content?

I created a group of users for my main blog but the blog is still readable by everyone just pointing to the default URL... is there a way I can prevent people to read unless they have an account and they are logged?

My apologies if this is a FAQ: I searched around but I was not able to find an answer to it.

Regards,
blackdir