Hello newcruiser2, welcome to Cruise-Chat!
When you type in all caps, it means you're shouting... .
The Mariner is one of my favorite ships. You're going to be in awe when you get aboard. Making sure you have the right documents is simple ... just go to RCCL's web site and move your cursor over the "BEFORE YOU BOARD" and click on "On line check-in". Just follow instructions. There will be other information on documents on the site.
You will be docking at a pier in St. Maarten and San Juan. As a first time cruiser, you will be overwhelmed with all the exciting thing to do. Don't miss the ice show! It's free, but you need to get a ticket; there will be announcements on when and where to get the tickets.