Changing out elements in responsive design

I am trying to make my website responsive, using an existing Dreamweaver bootstrap template. I did the tutorial (Responsive web design basics), and it was good except for one thing: it did all of the formatting in code. I would really prefer to use DW and stay out of code. Can anyone refer me to a tutorial for DW that actually uses DW's features? I understand I have to tweak code sometimes, I would just rather not do everything there. My main issue at this time (there are others, but I'm hoping a good tutorial will cover all of it): I want to use different artwork for my header in the various screen sizes, so need to make the different versions show up/go away as the sizes change.