I would be interested in joining your group: 'the anthropology of Islam in Europe'. I am currently involved in a research project with Ecole des Hautes Etudes en Sciences Sociales in Paris related to this topic. It would be nice if we could share ideas and information.
I'm afraid that the only way to adjust your privacy settings once your group has been created is to delete it and start a new group with the correct settings. All of the existing messages, comments, images and posts on the group will be lost when you delete it, so be sure to back them up before creating the group again.
Sorry about the inconvenience, but Ning is rather inflexible in this way.
This tutorial shows how to set your new group as public (see screenshots).
In the spirit of openness established here, we encourage that all groups have their privacy permissions set to public (so that any
member can join without an invitation and display the
group icon on their profile). You can read more about group settings here.