You will probably have to add something in the note section of all the contacts that you want to have in the smart group. At least that's how I read it.
Smart Groups are group addresses that Address Book automatically updates with new contacts when they fit the criteria you've specified for that group. For example, if you create a Smart Group for all the members of your swim club by searching for "swim" in the Note field, then every time you add or change a contact and put "swim" in the Note field, that contact is automatically added to your swim club Smart Group.


"Choose File > New Smart Group.
Enter a name for the group.
Use the pop-up menus and entry field to specify the search criteria for the group. Click the Add button to refine your search with additional criteria.
Select "Highlight group when updated" if you want to see when Address Book adds or removes a contact from the group.

You can also create a Smart Group by entering a word or phrase in the search field in the upper-right corner of the Address Book window, then choosing "Save Search" from the Action pop-up menu near the upper-left corner of the Address Book window.

To edit a Smart Group, select the item in the Group column and choose Edit > Edit Smart Group.

To rename a Smart Group, double-click the name in the Group column and enter the new name."