As soon as you have created a new event your invited players/parents will be notified of the new event and be able to RSVP confirming their availability. To check the status on availability follow these steps:
Open the app and go to the chat tab
Click on the group for which you want to check responses.
For the event you can see a summary of the number of responses as follows:
Screenshot 1: Summary of RSVP count
Click on the View all responses option to get a detailed report of who responded.

Actions
Mark Attendance: This brings you to the screen for recording attendance at your events.
Status
Yes - Available for your event
No - Not Available for your event
Not Responded - No RSVP submitted
Unavailable - Automatic response as a player/parent has marked themselves as unavailable for a period of time.