How do you get cream?

Excuse me, I'm a bit confused about something. Could you possibly explain to me in simple terms how one goes about obtaining cream? I've heard it's used in many recipes, but I'm not sure where to start. Is it something that's commonly available in grocery stores? Or do I need to go to a specialty store? And once I have it, how do I store it to ensure it stays fresh? I'd really appreciate your help in clarifying this for me.