full width header

Hi everyone,

I have to question, was looking for it on the forum but couldnt find it.
The website is naruto-naruto.com and i would like to do 2 thins.

– the first thing, how to I make the header uploaded by wordpress a full width. so it goes a 100% from left to right. right know I’m think the size of the upper body contains it, and i dont know where to make the change, to get it full width. (the website is above, and I use twenty twelve)

– the second is, how do I make it a three colum layout?

Thanks in advance,
Kevin