A FZ .fzpz part file is a zipped package of 4 svg drawings and 1 .fzp control file. To make a part you edit a part in FZ and select File/Load image, and that loads the svg for one view.
If it’s just an image for a view you use buttons at the bottom of the CORE bin.
It’s too hard to explain because the details aren’t clear, so here are some vids.