Adding the Web Service Reference (proxy class)
Next, we are ready to ad the web services to resolve the references for the exposed methods. Select the project folder > Right-click mouse > Select Add Service Reference.
In the Add Service Reference page click the Advanced button.
In the Service Reference Settings page, click the Add Web Reference button.
Remember that the web service was hosted at the local IIS web server. Select the second link: Web services on the local machine.
Click the Service1 link which corresponds to the web service that we need.
Just leave the web reference name to 'localhost' and click Add Reference button.
You should see the added web service reference in the Solution Explorer.
Build the project and make sure there in no error.
Run the project without debugging.
Key-in the X and Y values to be added. Confirm the result of addition operation is correct.