Hi Cheryl Ann. I believe there are two ferry systems they are talking about here:
1.From Charlotte Amalie,it is a longer ride.
2.From Red Hook to Cruz Bay, St.John
From Charlotte Amalie where your ship docks, get off the ship,there will be many taxis waiting,just tell them to take you to Red Hook for the ferry(the cost is about $10 per person for the taxi)
Once in Red Hook you need to buy a ticket for the ferry ride to Cruz Bay, St.John, it's about $6.10 pp. After the ferry, take another short taxi to Trunk Bay, I think it's $6.
Don't worry those taxi drivers,they'll help you,just tell them where you want to go. But to be safe, print out the ferry schedule,so you know what time you need to get back to the ship. Keep in mind that it takes longer to get back because of the heavy traffic in the afternoon.It was our first time to Trunk Bay back in 2006 too, my kids loved it too much,so we'll go back next month
Cheryl Ann, other cruise chat members gave you some great advice, I was confused my first time too but thanks to them I took my first cruise!
I hope I'm giving you the right advice because after all, this upcoming cruise is only our second cruise. Other members, please correct me if I'm wrong