From the Participant side:
The participant will receive an invitation email to join the team. In the email is an Accept button as well as a Decline button.
After they click on the Accept button, it will take them to the login screen.
Once logged in, the first thing that pops up is the Invite. They will need to Accept or Decline again.
If they Accept, it will begin the registration process and charge all fees associated with the program as well as require agreement to any waivers set in place for the season. Then they can submit payment.