There are various ways to Add members to a group
Before adding members to a group you will need to create the group. If you need any help creating a group please review this article.
Users will need Full Write Groups permissions to perform this function.
First, navigate to the group. Select the Members Tab, and then select "+Add Member"
This option only allows you to add one member at a time.
Form Submissions/Group Registration
Users will need Full Write Forms permission to complete this task.
To add members to a group based on a form, first you'll need to create a group registration form. If you need any help building the form please review this article.
Next, you'll need to add the form as the group registration form. If you need any help attaching the form please review this article.
Navigate to the group registration form. Under the settings tab of this form please select "Group" under the first dropdown. Note: This will automatically add the individuals who fill out this form to the group you select.
Mass Change option within the People Query Builder:
Users will need Reporting and People Mass Change permissions to complete this function.
To add people to a group from the People Query Builder you'll first go to
Reporting > People > and build a query that returns everyone that should be added.
Then go to the Actions dropdown menu at the bottom of Query > select Mass Change.
Finally choose Add to Group in the right drop down (see screenshot), then select the group you'd like to add them to: