I set my header image to display a 1280 x 400 pixel slideshow on the home page, but would like to either delete the image container, or change the container size from 400 high to 150 pixels high on posts and pages below the top level.

Is there a way to do this? (I am fairly new to the Atahualpa theme & Wordpress)

I tried suggestions from older posts, but these result in displaying the suggested code in the header instead of enacting the code. I pasted the code into the Configure Header Area.

did you look in the FAQ - Atahualpa : Header forum?

Yes, I followed the advice in your 2011 post to insert the following in the ATA Add HTML/CSS Inserts in the HTML Inserts:Header selection.

The result is having the code display in my header. Surely I am missing something. Here is the page.

http://www.capaytest.artnsoil.com/in...le/yocha-dehe/

where EXACTLY did you put that code?
go to ATA->Export/Import settings - do an export and attach teh export to a reply (use the paper clip icon)

Attached is the file. I pasted the code into the Atahualpa 3.7.18 Theme Options/various content items/Add HTML/CSS inserts/HTML Inserts: Header

Oops, the last export file for my site/page was incorrect, here is the correct file. I placed the brackets to enclose the code and now the code is not displaying, but the header image container is still displaying.

ok, go back and read the post in the FAQ and then go and see where you put the code.

This is a test and you will be graded on your reading comprehension, direction following and debugging skills

OK, Thank you for the clarification.

I did put the code in the CSS inserts window:
body.page-id-306 div#imagecontainer {
display:none;}

It does remove the images, but not the container, leaving just an empty container. My hope was to remove the container on pages with more text and listings.

Is it possible to get rid of the container, or give it a height of "0" on some pages using CSS Inserts?

sure, with the same body selector add '...div.header-image-container-pre {height: 0px;}