From Skype: http://www.skype.com/intl/en-us/support/user-guides/call-with-video/
Make sure you’ve got a webcam and check:
– it’s plugged into your computer
– you’ve installed the software that came with it
– it’s switched on.
In your Contact list, find the person you want to talk to.
Click on them.
In the main window, click the green Video call button.