Group leaders can opt to record who belongs to their group in the web site (we show you how later in the walkthrough).
As a group member, you can list the members belonging to the same group. On the group page you will see a 'Membership list' link like this:
Click the link to see a list of members. You will also see links to allow you to contact individual members (subject to them giving their permission) and to email all group members that allow you to do so.