Error messages

My site at http://billzarchy.com/site now displays the following error messages:

• Notice: Undefined index: images_root in /home/bzdp/billzarchy.com/site/wp-content/themes/atahualpa-5/header.php on line 43
• Notice: Undefined index: images_root in /home/bzdp/billzarchy.com/site/wp-content/themes/atahualpa-5/functions/bfa_header_config.php on line 149
• Notice: Undefined index: widget_center_top in /home/bzdp/billzarchy.com/site/wp-content/themes/atahualpa-5/index.php on line 11
• Notice: Undefined index: widget_center_bottom in /home/bzdp/billzarchy.com/site/wp-content/themes/atahualpa-5/index.php on line 51

Any ideas on how to deal with these? They appear on every page. Thanks.
BTW, I just realized that I haven't donated to BFA in several years, so I'm going to do that now. Thanks for your great work!