website and Facebook

I am a bit like Marcel Marceau in the glass box so here it goes. I am trying to create a link between the a members only page on my organization’s WordPress website and our Facebook group created by someone else. All of the information about doing such a thing that I have been able to uncover has been rather specific (i.e., install/set up specific plugin). I need to learn about this relationship (and the jargon) on a broader level so I have a better understanding while creating the link in my website. Does anyone know of such a resource? What is the relationship between MY facebook account and a GROUP account. When I am setting up the link can I get the GROUP Application ID, API key, and secret or does the person that set up the group have to give that to me? I have other questions but these give you the jist of my ignorance.

Thanks