If you want to get into the metro design business here is a link to the latest design curriculum being offered to professors and students.  You might want to take a look at it.

Zoom over the link:

https://www.facultyresourcecenter.com/curriculum/8999-Designing-for-Modern-UI-Module-1.aspx?c1=en-us&c2=0

And you don’t have to be a professor or student to download this document.

It gives you an extensive review of what Metro is, not now how.