Here is the technique:
--double-click the Background thumbnail in the Layers Palette/Panel while holding down the Alt key -- the result is a conversion to Layer 0
--drag that layer to the New Layer icon to create a Layer 0 Copy
--apply a mild Gaussian Blur to the entire image
--click on the Mask icon in the Layers Panel to create a mask on the top layer (Layer 0 copy)
--select the paintbrush and choose the color black (be sure the Mask on Layer 0 Copy is selected)
--paint with black the portions of the image that you want to come back into sharp focus as follows: a)for maximum sharpness = maximum erasure of the Gaussian blur (e.g., the eyes and lips and perhaps the hair), use 100% Brush opacity b) for areas in which less sharpness is desired (e.g., the cheeks), use a lower Brush opacity so that the Gaussian blur is only partially removed c) for the background, consider performing no painting at all, thereby leaving it completely out of focus
P.S. Here's a helpful technique that I learned from some of the recent courses that I have taken: While holding down the Alt key, click directly on the Mask and a large image will appear of what you have "blacked out" on the Mask so far. This helps to define areas of the image that you want to paint but have missed. Alt-click on the Mask again to return to your image.
