Tutorial : How to face swap in Photoshop

Here is the tutorial as promised :-)
Let's quit the unnecessary talking and get started :

For this tutorial we will be using the following picture :

(We want to copy the right face on the left girl)

Hilarious : Face Swapping / Facebombing

Ohh yeah... Again and again I find it very amusing when I find a similar picture on the internet.
For those who may not know yet : The procedure that happened in this picture, is also known as Faceswapping or Facebombing. You simply switch the face of one or more individuals with one that looks really funny (e.g. if someone's grimacing) and the best part of it is, that all of this can be easily achieved by using modern picture editing software like Adobe Photoshop.