Can't add widgets to either sidebar

I just downloaded this theme today, and also upgraded to Wordpress 2.8.5. I really like the theme so far, and I think it's the one we're going to end up using, but I can't seem to make custom sidebars. It's been a while since I last started a Wordpress site, but I seem to remember all I had to do was move the widgets to the sidebar I wanted to use and save it and it would automatically use my custom configuration. With the new WP now, I don't see anywhere to save the configuration, but it's just going back to Atahualpa's default sidebars when I leave the page. Am I missing something somewhere or is it that Atahualpa and WP 2.8.5 aren't quite compatible yet or is it something totally different? I hope that makes sense! Thank you!