interesting wp theme

Hi WordPress community!

First post around. I have a ‘kinda’ question. I developed WordPress themes before, but only simple ones.
Last week my ‘lovely’ designer came up with a really interesting design for one of our customers. Nice, good looking design, but when I found out that the customer wants his design to become a WordPress theme…
The structure of the page looks something like this. This is the inner page of the site, the home page drops the ‘sub page’, so basically it only contains the ‘header’ and the ‘content’.
I really, really need fast help for this one. I want somebody that has to much free time and is the second born Mother Teresa to explain the possible structure of the page, or, what could be more than helpful to provide an example of a theme that looks like this one ( or at least has the same functionality ).

Thanks,
Seb