You can view the structure by navigating to Services -> Web Service Proxy -> <your imported wsp> -> Policy -> WSDL Policy Tree Representation and then you can scroll down to the operation you want to configure or examine.
To call a specific operation you have to create operation specific messages using the WSDL (use for example SOAPUI to get them generated automatically) and then point them to the ip and port of your WSP. For example a test message for Add - operation generated from the WSDL:
<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/" xmlns:tem="http://tempuri.org/">
<soapenv:Header/>
<soapenv:Body>
<tem:Add>
<tem:intA>?</tem:intA>
<tem:intB>?</tem:intB>
</tem:Add>
</soapenv:Body>
</soapenv:Envelope>
--HP
#DataPower#Support#SupportMigration