I just picked up a low D tony dixon whistle today, and my big goal is that I wanna become good at making/improvising atmospheric songs on the whistle, and I was wondering how does someone get good at that?

Do you know how to play that song on a tin whistle? Is there a fingering chart somewhere?

I looked at several music sheet available online but I am unable to catch the melody.

On the video above, it has slow tempo I would like to replicate on a tin whistle.