You can find groups to join by visiting the Affinity Group Directory.
If you have been invited to join a group you can see your pending invites by clicking "my groups" on the teal colored main navigation. Then click "pending groups." To join a group, click "accept invite."
At any point you can view all of the groups you belong to by clicking Groups in the main Trellis menu and then selecting My Groups
You can search or sort these groups to help you find them more easily.
Further Questions? Contact the Trellis team at firstname.lastname@example.org