Ahoy there, Scott! Welcome aboard, and thank you so very much for your question.
Disney Cruise Line has a lot to offer, both in
onboard experiences and
port adventures. You can begin making those reservations based on your
Castaway Club status. If you've never sailed before, you can book your reservations beginning 75 days prior to sailing. Silver Castaway Club Members can book 90 days in advance, Gold Members 105 days, and Platinum sailors can begin booking 120 days prior to sailing.
When you log in to your reservation, you'll see a tab that says "Already Booked." When you click that, a drop-down menu will appear, and you want the link that says "Book/Manage Cruise Activities." From there, you'll be able to begin making reservations for everything you might be interested in doing.
Scott, I definitely recommend you make the reservations for the things that are must-do activities as soon as you can. Some of the most popular options can book up. If there's something you really want and it looks full, you can still go to guest services on embarkation day to see if there might be space available.
I hope you have a most magical high-seas adventure, Scott!
Anna