Use the Liquify feature to make the program detect people’s faces and to then edit, enhance, and deform those faces. You can also similarly stretch, shrink, or deform any part of a photo.
Facial Features [Shift – X] – when this function first loads up, any faces that are in the picture are detected. The detected faces are each marked in the picture with a blue square. The face that is currently active for editing is marked in red. Selected Face on the right lists all of the detected faces. Use the controls to adjust a face’s Face Shape, Eyes, Nose, and Mouth as desired.
When the icon 
is active, changing a property for one eye will automatically change the same property for the other eye.
Move – click and move individual parts of the photo to deform them. Use the other tools here 
Stretch, Shrink, 
Rotate Right, and 
Rotate Left for stretching, shrinking, and rotation.
Smoothing brings the picture back towards a more natural look, and 
Restore removes the effect completely.
More Information
Slimming in ZPS X? Use the Liquify and Facial Features Tools