Sobriety counter

Ok I've been trying to create a sobriety counter and its just not working... At all I need help oh plus I'm new at this whole thing so I got sober August 20th 2016... I don't know what I'm doing I've tried different codes like copy and paste and I just can't figure it out...

If you want to just count days since that date write something like

"Ehy i am sober since $tf(2016y8M20d, D)$ days!!"

How do i get years and months?

I found this code online but I can't figure out how to get my sober date in it