I can give you some basic info to start with.

You've got a Hydrangea macrophylla that appears to have been greenhouse grown for sale in a florist's or grocery store. It can be planted outside and, ultimately, would probably do better in the ground than indoors. First, it will need to be slowly acclimatized to the outdoors. They usually prefer morning sunlight and afternoon shade. It will benefit from winter protection.

Beyond that, I'm sure there are expert members here who can give you lots of useful info! Best of luck with your new acquisition!

A lot of these hydrangeas can be planted on the ground outdoors in warm climates but the industry treats them as annuals, meaning that they want you enjoy the bloom and then dispose of the plant. Since it is impossible to know if it is winter hardy, one should assume otherwise and provide it with winter protection once planted outside (hydrangeas do not do well inside). An alternative would be to grow it in pots/containers and bring it inside during the winter months (start by trnaplsnating it into a container that is 2" wider) using an acidic potting mix, water as soon as the potting soil feels it is starting to dry out and fertilize frequently as the frequent watering leech out minerals. Its eventual size is hard to predict since we do not know much about the plant (I would guess 3-5' in cold climates with a short growing season).

Great! We would like to plant it in our yard. How to do the winter protection on it? We are in Boston area. It is very cold during the winter.

One common way is to build a cage around it in the Fall and fill it with some material that will help protect it. See the link below.

Here is a link that might be useful: Overwintering hydrangeas