Also, to make sure only the people in the choir have access to things like the sheet music and line MP3s, there's a way to lock posts so that only members of the community can see them. When people request to become a member, the maintainer (in this case, me) has to approve them, so that way we can make sure who does and doesn't have access to our internal materials. For all members-only posts, there is a little lock icon next to the entry, that way members who are signed in can differentiate between what's publicly posted and what isn't.
Additionally, we can also make all comments to any post, public or members-only, subject to approval by a moderator (me, perhaps Anne, perhaps someone else). That way, no one will be able to post something on the blog until it's been approved by the appropriate moderator. See, isn't that helpful and easy?