Hi Mobish, and welcome! It's pretty easy, actually. And we're happy to help. I'm excited about this cruise, too. I'm going with my sister. It will be my tenth
Disney Cruise and her fifth.
Here's what you need to know: on your reservation it will tell you when you can book your activities. You must be paid up in full to do this, so make sure you pay on time! Your activities fall into a few categories (1) adult dining (2) port adventures (3) spa (4) onboard stuff.
You must have a log-in account with Disneycruise. If you don't, go make one right now!
(1) Adult dining is at Palo's the adult-only restaurant. It's very nice if you are celebrating a special occasion or for parents who need "date night" away from the kids. All the meals on the ship are included in your reservation, including room service, except Palo. Palo will have dinner every night, and sometimes (sea days, generally) brunch and or tea. All meals are $30 per person, plus alcohol and tip. Personally, I rarely go to Palo's, but I'm unusual in that.
(2) Port Adventures is a fancy name for tours and whatnot in the ports. You can acquaint yourself with what types of things are available by cruising the website, but the actual offered tours may vary. So get a sense of what you might want to do, but be flexible, in case that particular tour isn't available. Also know that you do not have to book a PA; you can tour on your own or stay on the ship. Lastly, know that experienced cruisers have seniority for booking, so it's possible that your first choice will be sold out already. But also know that they get cancelled and changed, and you will likely have other opportunities to book (even aboard ship!)
(3) Spa treatments; again, you can look around the website and see if something interests you in the spa. You should know that on port days the spa tends to run specials, and they are also, on port days, fairly amenable to deals. If the special is for, say, a 30 minute XXX massage for $Y, they'll usually give you a different type of massage for the same price on that day.
(4) Onboard stuff. On a seven night cruise there will be character meet and greets, like a breakfast where the characters come and say hi to you. These are for no additional charge, but you need a ticket to attend.
The other things to consider are how to get to the cruise and back and whether you want Disney's help for this, and also whether you want to prepay your tips. Lastly, as the time grows closer, consider whether you want to prepurchase a photo package or wine package and whether you want to order a going away gift (left in your stateroom).
Welcome!