How do I add a date to the mobile calendar from the game?

Hello I wanted to add an event date to the calendar on the mobile phone (IOS/Android) when the player clicks a certain button but I cant find a function that can do such a thing.

I have another question and I hope this isnt against the rules but I wanted to know how to add a youtube video to my game? (enabling the user to play certain youtube videos from the game).

Thanks in advance.