How to use the service oauth (DF 2.0)

Hi

Thank you, I managed to start the integration of my app.

I could configure the service and already with the vendor code (Facebook).

My question is as to how to complete the field query_string_from_callback_containing_authorization_code_and_service_name the URL below.

POST
https://your-url/api/v2/user/session?oauth_callback=true&{query_string_from_callback_containing_authorization_code_and_service_name}

Thanked.