You don't have to. It's unnecessary. It reads better without it. The only reason I can think of as to why it might have been added is that these words are meant to be read aloud. Consequently the comma after 'Day' would indicate to the speaker that they should pause there. But really, there is no reason whatsoever to use a comma there. It's redundant, and like I said I think it's better without it.

Yes, it's from that website. And a speaker says a comma after a word 'day'. Thank you for your answer :)

I'd say the first comma is simply wrong. I found the text on this website - http://www.learnenglish.de/dictation/edictationaprilfool.html - and it looks like a mistake in the transcript. There's no reason to put a comma there.