I am looking for an excercise that I can do to flatten a stomach after a c-sect?

No exercise will flatten your stomach, it takes diet and exercise. Situps, crunches, and other ab exercises only build muscle under the fat, they dont make the fat go away. Also, you cant choose where you want the fat to go away from, some people want to lose fat in their stomach, but dont want their butt to disappear, that just doesnt happen. Where you lose the fat from is based mostly on genetics and sex (male or female).