Deciding which WordPress theme to use

I’m a volunteer for an education foundation with an existing www.ads-software.com site that we need to completely revamp. I recently completed an online WordPress.com course, so I’m a novice. (I built a retail website with Monster Commerce in 2003 and have contributed to a hospice intranet site.) The education foundation director favors the low-key “look” of this website — https://www.cfgreateratlanta.org/, but I have no idea which WP theme to choose. Preferably it would be one with left navigation, one column, and right sidebar or widget. He also is contemplating using Wufoo online forms, which I’m not sure we’ll need with all the WP plugins. Advice would be greatly appreciated!