Heat oven to 325°F. Generously grease 12-cup fluted tube cake pan with shortening or cooking spray. Make cake mix as directed on box, using water, oil and eggs. Pour half of the batter into medium bowl; set aside. Divide the other half of batter equally between 2 small bowls. (You will be left with 3 bowls of batter.) Add red food colour to 1 of the small bowls and mix well. Add green food colour to the second small bowl and mix well.