The concept is called a Good Job Note, and the method is easy to follow.
1) Select a Child, Teen or Adult who has acted toward a "neighbor" as Christ would have them act, and address the Good Job Note to them.
2) Salutation line: Dear Peter,
3) Tell the exactly what you noticed them do. "Today in Sunday School I noticed you helping Sally pick up the mess next to her chair, even though no one asked you to do it."
4) Tell them how it made you feel: "I always proud and excited when one of our students shines the light of Christ on others."
5) Tell them what will happen if they keep it up. "If you keep helping others like that, Jesus will call you a 'Good and Faithful Servant.' "
6) Close the Card. There is a visual example of this on the bottom of the page.