See? Already you've friends made!
How exciting for you! I've been on QM2 alone and loved it! I hope you will.
Get to Red Hook "earlyish" and as soon as boarding begins you just go through security and register and go on. You'll go to your cabin. Do whatever. Then you might want a bite to eat ... go to Seven Deck and they've Kings Court and food service, buffet/cafe style, so do yourself a tray and maybe get a table in one of the window bays where you can watch passersby outside. At one o'clock-ish it won't be too crowded; by after three o'clock it will be. Then you might walk around the ship and get familiar with it. It is a large ship but it's really easy to get around. Probably at half four or toward five there'll be a boat drill. Instructions are broadcast and you go get your lifejacket from your cabin and go to your assigned station. Staff is all over the place guiding you.
You'll meet people walking around, at the drill, outside when the ship sails (hope it's sunny & dry for you) and certainly during the "ahhh" moment a bit later when the funnel almost hits the bridge as you go under. Photo op here!
You'll meet people at your dinner table. Sometimes on a cossing you can see them all the time, or only at dinner. You'll meet people in the gym, the library, the Commodore Club bar and other bars. At lunch you can use your dinning room, Kings Court, or do a pub-style lunch in one of the bars. Your daily bulletin will list activities you might want to go to; there'll be people there. The photo gallery "do I really look like that" always has people browsing.
On a real cruise, a ship goes from port to port to port, stopping for a bit of time at each, while the load takes day trips off ship.
On a transatlantic crossing (a direct line point to point, New York City to Southampton, why they call the ship a liner) you'll have days of leisure; outdoor activities, indoor, whatever you want. You can be as active or as lazy as you wish.
Some say there is nothing to do at sea and just not enough time to do it! I think you'll take to it easily, being excited about the prospect. You can get up early and have a bit of early-bird room service to get you going, then go to breakfast, have a walk about, go to activities, get ready for lunch, do that, do more activities, take a swim, look in the shops, have Tea in the Queens Room (always an easy place to share tables and join up with people), stop by the bars, dress for dinner, stop by the Casino and try your luck, or not, go to the films or the shows, go dancing, go to the disco and dance and/or look, take a spin around the decks, "hear" life at sea!
You can be with people or be alone as much as you wish, sleep as much as you want, or not at all, go to all the posted activities or none. The time's your own, what you make of it. It can be great fun. As they once said, it is the only way to cross!