Hi Charan,
You will need to complete your ESR portion till Service interface, mapping can be done later. Once this is done u may take the WSDL URL by going to Sender AGreement in case of a classic XI scenario or if u using a AAE then thru ICO.
The URL and username passowrd will be used by the third party to authenticate onto the PI server.
Let me know in case of any doubts.
Regards,
Sriram