Fixing top nav; moving above header in twenty twelve

Hi there! First time posting. I’m a relative beginner to WordPress but am fairly comfortable with basic CSS. I’ve searched the forums for the past few days but haven’t found anything that works, hope someone can help.

I’m trying to move my navigation to the top of my page, and keep it fixed so that as I scroll, the nav stays and the body scrolls. Right now some of the changes I’ve tried have messed with the way my text looks, or haven’t moved the nav to the top.

Here’s my site: http://popandsizzle.com
Here’s an idea of what I’m interested in: http://paulina-farro.squarespace.com

Any help would be MUCH appreciated, thanks!

PS: Using Twenty Twelve.