How do I put a logo image on top of the header in TwentyTwelve?

I am trying to put .png logo with transparent background on top of the header image on my site.

The link is annarborbagua.com. The media is at http://annarborbagua.com/wp-content/uploads/2014/09/YSBI-Branch-FB-Profile-01.png

Thanks in advance for any tips on how to do this!