OP, there are people to direct you through the whole process. As others have said, since you are taking the bus from the resort, you will get a letter the night before that gives you details on luggage pick-up and meeting the bus. If you have any questions on this part, the morning of the cruise, there will be a cruise representative in the lobby of the resort (generally where they tell you to meet for the bus), I have found the resort workers don't know the answers to your bus or cruise questions so don't bother. You'll recognize them by their uniform -- they have light blue "sailor" type tops. While they start luggage pick-up at 8, you do not need to be in your room for them to collect your luggage. If you won't be there, make sure your carry on luggage is well separated from the bags you want them to take (which you should place just inside the door).
Taking the bus from the resort to the port can be the most convenient but is not the fastest way to get there. So just know your pick up won't be until closer to 11am/12pm and your arrival to the port may be closer to 1 - depending on how many stops you have to make before heading to the port. So we usually just plan a relaxing morning at our resort.
Once you are at the port, the bus drops you off just outside the entrance. You will go in and go through security - just like at the airport with metal detectors and bags being x-rayed. Once through there, the only way to go is up -- the escalators or the elevators. At the top, there will be individuals there to give you a medical form to complete and direct you to the right line. Once you are checked in, chance are (unless things are very behind) you will be able to walk right on the ship. In Port Canaveral, you can't miss the way to the gangplank -- right though the Mickey Ears.
I know it's nerve wracking since you haven't done it before but Disney makes it easy and has people to guide you all the way through. So relax, it will all be fine!
Once onboard, your rooms are typically available at 1:30, so if you are there before then, you do have to carry around your hand luggage until 1:30. Do download the
DCL app before you get on the ship - you can use that throughout the cruise without using any internet. You do have to sign up for the free internet package the first day. I usually wait until we are settled in the cabin -- there will be an information sheet in there to guide you through the process. Luggage starts being delivered shortly after cabins are opened and most is delivered by time the muster drill is over. So you may get lucky and get it early or you may be one of the last and if you head to the Sail Away deck party right after the muster drill, not see your luggage until right before 1st dining/show.
Enjoy your cruise. Hope you budgeted $250 to at least book a placeholder for the next cruise you will want to do!