Can I target audience of a specific facebook group (not a page)

If I understand your question correctly, you want to create a group not a page, correct? If that is the case you can create a group open or closed group that you can invite people to join.

The difference between the 2 is open group anyone can join, closed group they have to be added by an admin.

Thank you  Edward  I think my question is not clear

when I create advertisement  in facebook  How can I create audience of a specific on facebook group