After selecting the "Client" tab in the Settings page, select the "Client Lookup" tab.
Select the client you want to add to a Group by entering the client's name, primary e-mail address,
or telephone number in the search field or by finding the client in the list; once you have
found the client, select "Edit Profile" in the "Options" drop-down menu.
Select the group you want to assign the selected customer to by checking off the appropriate
Don't forget to click the "Update Profile" button at the bottom of the page to confirm your changes.