Trying to understand Adobe Sign Callback URL functionality

Dear Community,

I am relatively new to this whole process.  I am trying to build a .net site to process sending agreements out.  I understand just about all the functions to call and send documents.  What I am not understanding is the callbackInfo feature.  I am using the https://secure.echosign.com/services/EchoSignDocumentService22?wsdl  to make the documents.  I want to build a web service that will receive and process the call back.  I don't understand how this works.  From what I read, the callbackInfo will send the agreementId, status (i assume its the same filed name is in the restApi), and " information on the event that resulted in the callback".  Does anyone know how to do this?

        [WebMethod]

        [ScriptMethod(UseHttpGet = true)]

        public void Get(string agreementId, string status)

        {

        }