[SOLVED] Added center column widget showing in Widget area, but not displaying on pos

I added a center column widget in a previous version....my guess is it was 3.6.4, and then I upgraded to the current version, not realizing that I had a widget that might have been incompatible. The widget still shows in Appearance > Widgets, along with the text I placed in it, and if I go to ATO > Add new widget areas, it shows in the top box as a custom widget that could be deleted, but the widget no longer displays on my post pages, where it was.

I'm guessing I need to edit the index.php file to get it back on the post pages, but I'm not sure where exactly to put the code so the widget will display in the correct place (at the very top of all the post pages), and I thought I'd play it safe and check, because knowing me I'll end up breaking my blog.

The URL is www.theresasheridan.com/blog. I'm using the most recent versions of both WP and Atahualpa. Thank you!