Using a mask to white out a background and saving it to the jpg

[Ronda24274308cbqv]

I used a mask to blank out the background perfectly but I do not know how to get the picture to save or export looking exactly as the picture in Lightroom CC?  Any ideas?  I have been trying for hours.

[Rikk Flohr: Photography]

This is not currently possible in Lightroom. 
The Masking feature is designed to allow you to edit parts of an image - not remove/replace a background.