How do I join this session

You'll need to have Zoom downloaded on your device. When you've signed up and paid you'll be sent a Zoom link for the session, with which you can join the session

Are there other sessions following this one?

Yes, there is a session every Saturday morning at the same time 9:30-10:00 a.m. Regular attendance whenever you can make it is a good idea and makes meditating easier to do.