How can I increase the height of the header area so I can fit a larger header image into it without it overlapping the menus?

Look in ATO>Header Image. There is a height box.

I guess I asked the wrong question. I did that, and the header image is in there OK, but the gray bars that extend outward from the navigation menus are aligned incorrectly now. How can I move those down to account for the larger header image?
http://thedeskathlete.com/wp/

The part of the gray bars that are at the outside are a background image. You would need to edit the background image if you want them to align. They are called in ATO>Body, Text & Links.

I suspected that, but apparently modified the wrong image and abandoned that direction. It works perfectly now. Thanks so much!

PS the image I modified, in case anyone else runs into this was atahualpa351/images/background7.png