how to add period to app

Terra • Nurse. 27. Married for 5 years. 1 boy March 2018, another baby in the near future 🤞😍

I'm not sure if I'm missing it, but I can't figure out how to add a period to this app. I go to the <a href="https://play.google.com/store/apps/details?id=com.glow.android.eve">period calendar</a> and enter in my info, but it doesn't 'start" on today