How can I change the header background image on JUST the Gallery page of my site? Frontrow Template.

I'm using the frontrow template and cannot figure out how to change the header background picture on just the Gallery page of my site. I want a picture to appear on all other pages, but for the Gallery page I just want the header to be a background color. I tried entering a CSS code suggested by another user on a similar question, but it didn't work.