My teenage daughter has reached the age of puberty. How do I explain her about the menstrual cycles?

Just tell her straight what menstrual cycle is. And how she is not the chosen one but all girls go through it and it is perfectly normal. When she settles down a bit then tell her about your experience, when you had your first period and how it all went. http://www.mayoclinic.org/healthy-lifestyle/tween-and-teen-health/in-depth/menstruation/art-20046004 http://www.wikihow.com/Talk-to-Your-Daughter-About-Her-Period