To be able to do this you are going to need to use an app on the phone that allows for this. There are quite a few to be found on "Google Play". The most common one use is called "IP Webcam". However, this one will not work with "Skype".
If you want to use it for there, you would need say "DroidCam Wireless Webcam".
NOTE: Both of these are apps for your phone, not the computer.