If you want to watch people having sex on Skype then there are a couple of websites to visit:
1) Just go to a mainstream adult sex site, like p*rnhub.com and search for "Skype". I promise you will not be disappointed.
The other way is to actually connect with other Skype users, and see if they would be willing to have Skype sex with you.
There are actually chatrooms and forums where people go to meet other that want to have Skype Sex, but from experience it is slim pickings... But give it a go and see what happens!