Would like to add google custom search to site, using this methodology:

http://digwp.com/2010/10/google-cust...o+WordPress%29

If I wanted to replace the default search and put Google CSE in the same location, where do I add search box code:
searchform.php
-or-
header.php
-or-
/functions/bfa_header_config.php

I always avoid modifying theme files. I would put the code in a widget and position with CSS.

be great if Atahualpa followed this paradigm:

http://codex.wordpress.org/Child_Themes

you can create a child theme with atahualpa

So if I copy Atahualpa and rename directory to act as a child and then in child theme's style.css do I merely add:

Template: Atahualpa

and then i can modify the files in the child theme?

You copy the style.css and change the title to something like

Theme Name: Ata 377 child

and you need the index.php . after that you can do what you want.

It is not so easy. How do you think the wordpress on my website's blog /www.homedecornest.com/blog .I don't know how to add the google custom search to my website too.

homedecornest: this forum is for users of the Atahualpa and Montezuma themes. If you want to ask questions, you need to use one of these themes.