Each group has a Roster through which you can message the entire group. So, if you want to email all the first grade parents, just go to their group, click "Roster" then, next to "Bulk Communication," choose "Members." A message window will appear in which (behind the scenes) all of the group's members will be contacted. Write your message and then send. The note will be sent to their onCampus Inbox, and if their notifications are on, they'll also receive an email alerting them to the new message. If you want to message one person, just click the blue "message bubble" icon next to their name in the Roster.
Be sure under your personal settings, you have messaging "Notifications" set to "on" so you can also receive notices from fellow parents. It's a secure and easy way to stay in touch with the North Cross Community. Download an illustrated tutorial here.