Too much white space!

Hey there,
I’m totally new to wordpress, and it’s been quite the learning curve. I’ve seemed to have gotten my website, as far as design goes, where I want it to be. EXCEPT for the huge white space between the header and content and the footer and content.

I am using a child theme for twenty twelve.

Where can I reduce this huge white space/size and how? http://www.sarahnightingaleart.com Thanks!