Assuming you navigated the Foreground select tool successfully and now have a selection, then added a black layer mask.
As: https://i.imgur.com/cNu7SJM.jpg
That makes everything in the mask transparent. Click in the layer mask icon toggles active, make sure it has a white border.
https://i.imgur.com/HskAyDF.jpg
Bucket fill in the image canvas to show the selection.
https://i.imgur.com/ELcu2t5.jpg
Kill the selection, Select -> None
An alternative is:
Invert the selection Select -> Invert
Add a white layer mask
Fill with black.
As: https://i.imgur.com/cNu7SJM.jpg
That makes everything in the mask transparent. Click in the layer mask icon toggles active, make sure it has a white border.
https://i.imgur.com/HskAyDF.jpg
Bucket fill in the image canvas to show the selection.
https://i.imgur.com/ELcu2t5.jpg
Kill the selection, Select -> None
Quote:How do I keep the model visible and have the background disappear?
An alternative is:
Invert the selection Select -> Invert
Add a white layer mask
Fill with black.