Intergrate WPF App to A WCF Service. How?

I want to integrate my existing app to a WCF service. Do I need to dismantle everything and re-write it as a class that I can add to the WCF service or do I reference it as it is, inside the Web service? Please give me some leads. An example or some link will be appreciated. Thanks a lot.

Kumika

Do you want to host the WCF service in the WPF app? OR do you want to consume the WCF app?