How to change the header to the middle on the eleven40 theme?

I am creating a website using the eleven40 theme and I would like to move the header (the little rectangle in the top left hand corner) to the top middle of the page, with the menu links on either side, insdead of having it on the left with the menu links on the right. I’m pretty new to wordpress itself but I can deal with html on the stylesheet so if anyone has any methods for me to do this then it would be very helpful! Thanks guys xoxo