How to blur the background of oppo r9s photos?

The operation steps are as follows, for reference only:

Camera ~ Set as Front Camera ~ Slide to Beauty Photography and click a water drop mark in the upper right corner.

Or set it to the front camera ~ four □ keys in the upper right corner of the store ~ click on the colorful filter ~ click on the penultimate water drop sign in the upper right corner, so that you can blur your beauty while filtering.