Header Question

Is it possible to add a larger image into the header? Something that would stretch across the full length of the upper nav bar – and still include the buttons for “About Us” and the like?

Right now I just have a very very small logo that I cannot make any larger within the confines of the space provided. I want to be able to make it much larger so when people visit the site, they will know where they are.

Any and all assistance is greatly valued!

Thanks!