You can add users to existing groups either by opening and edit the group or by editing the user account. See the two examples below.
To note: In order to be able to add a user to a group, the user needs to have an existing user account first. If the user account has not been created yet, you will find a guide on how to add users here: How to add users.
1. Go to People > Groups
2. Open the group that you want to add the user to by clicking on the gear
3. Search for the name or the email address in the section "People" and add them to the group
4. Don't forget to click on "Apply changes".
Example 2 (available to administrators only):
1. Go into People > Users
2 Open the user account you would like to edit.
3. Through these fields it is possible to easily add a user as a member, owner, admin or give the user the reading rights to one or several groups.
4. Search for the group and select the group you want to add
5. Don’t forget to Save changes.