How do I get one of those little Elves for Christmas?

See today was read-all-day-pj-day at my school. my teacher said that you could bring a small stuffed animal. So my friend Emily-Grace brought her elf named Molly. I asked her what it was. She said it was an elf from the North Pole. She said that you write a letter to Santa and bring out milk and cookies or crackers and water. Then your elf will come to you. They are cute with merry faces, and their supposed to be elves disguised as toys. Please tell me more about them and how to get them. Thx