To bulk message a roster as a coach, go to:
  1. Hover over Groups and select the Team. 
  2. From the team page, click Roster.
  3. Next to Bulk Edit, click Members, Parents, or All.
  4. In the screen that pops up, keep the message as Compose Message or change it to Send Via E-mail.
  5. Make sure the E-mail addresses or Inbox Messaging is sending to the correct users, fill out the message, and click Send.

The message will be sent to the users E-Mail or Inbox.