Transparent logo with Header Text overlay

Hi,

Have just discovered this lovely theme and am working through customizing it.

All makes sense but I can’t work out how to get the logo and header text to appear together in the header. I thought I read somewhere that you could get a transparent logo with the text written over the top?

In the examples on your demo there is a Pure and Simple with an & that is slightly transparent underneath the words Pure and Simple. This is what I am trying to create with a picture underneath the site title.

Any help you can give will be much appreciated.

Many thanks