In your PowerPoint presentation, select the slide you want to add spotlight.
Click . The visor mark will appear at the lower left corner of the slide.
Switch to slide show mode when you are done setting all the slides with spotlight.
Click and drag the gray cover to the location on where you want position it.
At the upper right corner of the spotlight, click to change the spot shape and the opacity level of the gray area, to close the spotlight, and to save the spotlight position, shape, size and gray area opacity level.
Spotlight
To add and set the spotlight setting in the slide
to change the spot shape and the opacity level of the gray area, 
to close the spotlight, and 
to save the spotlight position, shape, size and gray area opacity level.
