Inviting users one at a time to join your site can be
  time consuming. To save time you can add existing user groups to the current
  site.
    This task assumes you are in the Members component of the desired
    site.
    The process of adding a group involves searching for the group,
    assigning a role to the group as a whole, and then adding the group.
    Unlike adding users, no invitation is extended to the users in the
    selected group; the group is added immediately. The available user roles
    are Manager, Collaborator, Contributor, and Consumer.
    - Click Groups beneath the banner if this page is not already selected.
 - Click Add Groups.
 - 
        Search for and add groups.
        
- 
            In the Find Groups to add to this site
            box, type the full or partial name of the group you want to
            add.
            
You must enter a minimum of one (1) character. The search is not case sensitive.
 - 
            Click Search.
            
The list displays all groups matching the specified search criteria.
 - 
            Click Add to the right of the group
            you want to add.
            
The group appears in the Add these Groups box.
 
 - 
            In the Find Groups to add to this site
            box, type the full or partial name of the group you want to
            add.
            
 - 
        In the Add these Groups box specify a role
        for the users of each group.
        
- To set the role for a group, click Select Role to the right of the group and click the desired role.
 - To set the same role for all groups in the list, click Set All Roles to at the top of the list and click the desired role.
 
Note: Click back to Site Groups to return to the Search for Site Groups page without adding any groups. - Click Add Groups to add all groups displayed in the list.