Whats the best way to code up in CSS a grid/tile type layout similar to Windows Metro UI?

I know there is a framework out there called Metro UI CSS but I want to learn about raw CSS for now (I'd consider if for rapid development further down the line).

If my page was to look something like this - http://understandingexistence.net/wp...ws-8-phone.jpg

Do I construct it by rows or columns?

How should i build the tile which is split into 4 smaller tiles?

Thanks.