Chives are a member of the onion family. The long green rounded leaves are snipped and used to flavor and decorate foods. The chive flowers can be used as well. We like to use them atop carrot leek soup.
Fresh chives are superior to freeze-dried but they will do in a pinch. Freeze dried chives can be purchased in jars in the spice section of most well stocked grocery stores. Look for fresh chives in the produce section of your grocery store.
You can plant chives from seed or for a faster crop purchase chive plants in spring in 2" - 4" pots from your local nursery. The plants are very pretty and easy to grow. They will die back in winter (depending on your climate) but typically grow back the following spring.
We're growing our chives in one of our raised beds but you can easily grow them in a nice pot or integrated in with a flower garden. As you can see here a California poppy took up residence next to the chive plant and the color contrast of the yellow/gold poppy with the purple chive flowers makes for very colorful garden partners.