In most cases you will only be a part of one group - the group that is created for your organization. You can join a group by requesting an invitation from the admin of the group you would like to join. You will receive an email with a link to join the group.
If you are a new user, you will be prompted to create an account with Perch. If you are having an issue with the link, you can join manually during Perch Signup and use the code in your invitation email when prompted.
If you are already a member, you will be prompted to log in (if not already) and you will automatically join the new group.
Alternatively, existing users can join manually within Perch. Just hit the Join Group button add_circle on the group page and enter your initation code when prompted.