Form change color

Question

Hello guys ,it is a long time since i did some programming , and i really dont remember a thing, so i have to start C# all over again.
i have created a form with a button on it . when i click the button the form  changes its  color to Red. what i want to do now  is  that when i click the button again it changes its color to white and to make it keep changing from  red to white at every click.any help how to do this please? thanks and regards.