1. Start by selecting the desired group from the list of created Groups.
2. Once you have selected the Group you're looking to add new users to, you will notice an “Add Users” button on the lower right below the listed domain names.
3. When you click it a dialogue box appears as per below with a list of users
4. Choose the users you wish to add by ticking the box next to their name and then click the “Next” button.
5. You will then be presented with a confirmation screen. Click the “Save” button and the users will be added to the group.