What to do if i wanted to know about the menstrual cycle. ?

Very simply: The ideal menstrual cycle lasts 28days with cycle day 1 being the first day of menstrual flow. During the next 14 days the brain tells the ovary to grow an egg which then ovulates. This 14 day length is highly variable among women. The next 14 days are almost always 12-14 days in all women and are when Progesterone is made. If no pregnancy, then after 2 weeks the Progesterone stops & period starts.