You're not being thick-headed - it's not designed to be used in the ways that we've used the gallery in the past. Whatever doc you're reading probably is taking it from the admin's perspective.
The two albums you see: one is a member album from Casey; the other is one I created (admin) to accumulate all photos that members wish to share.
If you want to "upload" photos to the 2025/06/15 album, create a personal album (from your Profile, lower-right), and upload your photos there. If you mark it visible, it will show up on the Gallery page as Casey's did. If you want those photos to be in the album under the Acton Launches category (the 2025/06/15 album), notify me and I'll copy or move the photos, and then you can either "hide" or delete your member album.
I created a message in the Launches forum last night regarding this scenario.