You must have "Tourney Admin" access to message tourney registrants.
  1. Sign in to the Tourney Tool.
  2. Click on the "title" of the tournament you want to message registrants from. 
  3. Click on the Registration tab, then choose Reporting
  4. Scroll down to the Message area, and click the Send Message button. 
  5. Choose to send the message to Team Managers Only or Team Managers and Registered Athletes
  6. Enter your message and click Send Message

NOTE: The messages are one way only. Registrants cannot reply to the message.