If you are new to cruising there is a whole world of adventure and discovery that's awaiting you at sea. I'll assume that you know nothing about cruising so I'll really just start with the basics. Most cruise companies offers packages that take you on boats that go to almost any destination in the world that you can think of.
They head to all continents and to hundreds of ports. It's up to you to decide which package you want, and it's up to you to decide what sort of cabin you want, depending on how much money you have. The range of cabins is huge from the huge two-story apartment on the Royal Caribbean's Allure of the Seas, to the 4 bunk beds cabin where you'll want to spend as little time as possible. Quite simply, it's entirely up to you as to where you will stay.
During your stay on board, on most boats, almost everything is all-inclusive. There will be some restaurants on board, and probably a whole lot of buffets where you can eat as much as you like after all, buffets are generally all you can eat. And while you may have an idea that cruising is actually quite a formal affair, you'll find that these days, as cruise companies have tried to make cruising something for the mass market, that there are now no restrictions on what you have to wear in order to eat in most restaurants. Those new to cruising will find out that there is, these days, still the elegance of the golden years of cruising, but a little less of the rigid formality that you may have an idea about. No, these days cruising is fun for the whole family.
There are a huge number of water parks and activities to do, some of the biggest cruise ships even have massive movie theatres that can seat in excess of 1,200 guests. These theatres are dual purpose, as they are probably also used as the venue for theatre productions. But that's only on the biggest cruise ship in the world the Allure of the Seas, by Royal Caribbean.
You of course do not need to go for such luxury on your first cruise. There are many other options available to you if you just want to take a cut price cruise and are not so interested in the high-class end of things.