How to fix a flabby tummy after having a baby? I had a VERY FLAT tummy, small waist before I got pregnant.?

Do I lose the flat from around my stomach before trying to do sit-ups and crunches or do the now?

What other exercises can I do besides sit-ups and crunches to lose the stomach flat?

Will running be good?

Before I got pregnant I weight 146, now I weight 155, 5’6, and 27 years old.