Hello,
I've never done this but my guess is that firstly something will probably need to be enabled on your sharepoint server, I doubt a webservice is going to be on by default.
Secondly there are guides about using webservices, including REST, in the product area of the portal. We provide HTTP and JSON VBOs for your use as a starting point, but the expecation is that you have the ability to use and improve these to fit your need.
