Combine 1 (14 1/2-ounce) can mashed sweet potatoes, 2 tablespoons brown sugar, 1 tablespoon reduced-calorie margarine, 2 tablespoons orange juice, and 1/4 teaspoon salt in a medium saucepan. Cook over medium heat 5 minutes or until smooth and thoroughly heated, stirring often. Stir in 2 to 3 tablespoons water, if necessary.