Feathering edges - Vignetting
1 Open portrait.jpg  
2 Make selection with Elliptical Marquee Tool around the head  
3 Select > Feather... 70  
4 Select > Inverse  
5 On keyboard use D and X key to switch between black and white.  Set background to white.  
6 Hit delete key to delete selection to the background colour  
7 Image > Trim - don't change any setting, and click OK  
8 Select > Deselect or Ctrl > D  
9 File > Revert to go back to the last saved version  
 
10 What will happen if you repeat this exercise skipping step 2 (feathering)?  
11 Repeat exercise, but before hitting delete key (in step 3), change background colour to blue  
12 Change background color by using Eyedropper and selecting colour directly from image (eg. skin tone)