http://marina-diamandis.org/ looks like a custom design, and in that case it's not something you shouldn't copy directly.
What you're asking for is a new site design or a new theme. There isn't a simple or easy way to make a different theme look like the one you linked—doing something like that would take some time and work.
If you'd like to start from the beginning and you're new to CSS, I would recommend looking at basic CSS tutorials as a start:
If you'd like someone to create an entire theme for you, then you may want to consider hiring a designer.