All courses require registration and pre-course work to be completed online.  A video illustrating how to begin this process can be found here:
New Referees: https://www.youtube.com/watch?v=C36tX3xyggs&t=
Recertifying Referees: https://www.youtube.com/watch?v=lZiVbXtPaLw&t

All entry-level grassroots courses require online learning to be completed before attending the course's associated on-field experience session.