Question about parts of the theme that aren’t widgets

I’m migrating here from another site, and trying to get set up with WP. I recently installed the theme AquaBlock to rebuild my site with. I’m trying to get up to speed on widgets, and that sort of thing, so I apologize in advance if this has been covered before, although I did search the archives.

Anyway, on my page, there are links for a couple of pictures (EntreCard, Advertise Here, etc), as well as sections for About (with a picture) and Popular Posts. However, I can’t find anywhere on WP where I change those sections. It’s not listed under the Widgets, amd I looking in the right place?

Thanks in advance for any help I can get here. I appreciate the assistance.