Twenty Twelve Edit

I’ve been trying to do this for hours.

http://www.potionbear.com/wp-content/uploads/2013/04/Untitled-1-1024×551.jpg

What I have: potionbear.com

All I want is a full-width header.

[Please do not create duplicate threads – http://wordpress.org/support/topic/simple-header?replies=8
or http://wordpress.org/support/topic/twenty-twelve-edit?replies=3 ]