Late period

I don't get this whole thing cause this is like the 6 time I had to put late period on my chart when I have to update it cause where is says record menstruation cycle I can't put never got it an every time I hit my period is late it just adds on 3 more days til I get it an so far have not got it at all tomorrow 4/6 would be 2 weeks late. Can someone help me figure out how to do this to where I can logging in that my period has not came yet on the home page where u put ur log info