How do I save a bunch of addresses as a group

Hello there, Mark.

It seems you were referred to us from the very Knowledge Base article that provides the steps you're looking for:

Mac Basics: Address Book.

http://support.apple.com/kb/ht2486

Particularly:

• If you want to address a group of people in an email instead of entering all their email addresses, create a group. From the File menu, choose New Group and enter a name for the group. Select the All Contacts group, to view all of your contacts. Then drag names from the contact list onto your new group in the group list.
• You can also create a Smart Group, a group that automatically updates itself if any contact fits the same search criteria you set for a Smart Group. To create a Smart Group, choose New Smart Group from the Filemenu, type a name in the Smart Group Name field, set your search criteria using the pop-up menus and fields. For example, choose Company from the first pop-up menu and type a company name in the field to create a Smart Group for people at that company, and click OK. Any contacts that match your search criteria will become part of this Smart Group.If you frequently send email to a group of people, such as all your coworkers,
  create a Smart Group, which automatically updates on its own

Thanks for reaching out to Apple Support Communities.

Cheers,

Pedro.