I saved a scene of this girl dancing and the "floor" saved with her, and when I called up the scene, some extra flooring crept in that doesn't belong where it now appears? how eliminate that?

You can delete the flooring

How did you save the scene? Did you use the export partial scene?

I’ve forgotten export I saved this into library where I’m saving characters. Should I screenshot the simple process. Is exporting better?

If you saved it as a character, then the floor somehow got parented to the character. Your best bet is to load the character into a new scene. Unparent the floor (parent it to the universe) and then resave the character.

Entire scenes should be stored under the 'Scenes' category in your Poser Library. Saving multiple items under a single category can lead to misplaced projects. It's advisable to save your work as external PZ3 files, which allows for organization by date and title. Relying on the Poser Library to preserve scene integrity is not recommended when all items are grouped into one category.

I'm uncertain how to save external Pz3 files. ?

drawn

File--Save As..., specify locations, hit Save.