Laura - when I look at your AW, your current logo is 210x54 - it fits but it is very small -
Laura Macky
Photography
Would fit the space better and allow you to use a larger font in your logo.
The header background however, does not fill the space on my screen. I've used a small repeating pattern rather than try to fit an image across the whole background. The new design is made to fit screens from phones all the way to people like me on large monitors. If you use an image, it needs to be able to fill the space no matter what. Colors and patterns are easier to work with in this case although I have seen a few people who used actual photos that really worked well. They tended to have a lot of solid colors though that blended into a background color well.