Green food color Candy pieces to decorate tree with Spread popcorn evenly in jelly-roll pan or on waxed paper-lined counter. In medium saucepan, combine margarine and marshmallows; cook over medium heat until melted. Add jello; continue to cook until jello is dissolved. Add food color and mix well. Pour evenly over popcorn; stir quickly to coat. With dampened hands, shape popcorn into cone shape. Decorate tree with candy pieces.