Help getting from US mainland to St John US Virgin Islands

I've been hunting around and piecing things together about how to do this travel, and I want to see if I have this right. To get to St John from US mainland it's most efficient to: \ - Travel to St. Thomas airport
- Somehow (?) get to the ferry terminal at Charlotte Amalie/Havensight?
- Book via this: https://stjohnticketing.com/charlotte-amalie-cruz-bay/

Sound right? If yes how to get from Airport to Ferry?

Thanks!!