You may add users to your group by sending them an invitation from your dashboard (as shown below).
Step 1: Navigate to your Dashboard in the top-right corner.
Step 2: Click on the invitations link on the left-side panel.
Step 3: Enter the email addresses of the users you would like to invite to join your group, and then click the red "send invitations" button,
If you need help with this, please just shoot a message over to firstname.lastname@example.org. We'd be happy to help! 😃