How to post data from Objective c to webservice C#?

Question

NSMutableString *soapMsg = [[NSMutableString alloc] init];
  [soapMsg appendString:[NSString stringWithFormat:@"<INSERT xmlns=\"http://viium.com/\">\n"]];

[soapMsg appendString:@"<firstname>"];
 //[soapMsg appendString:actionHTMLString];
 [soapMsg appendString:@"RAHUL"];

[soapMsg appendString:@"</firstname>"];
[soapMsg appendString:@"<lastname>"];
[soapMsg appendString:@"sharma"];
[soapMsg appendString:@"</lastname>"];
[soapMsg appendString:[NSString stringWithFormat:@"</INSERT>"]];
[soapMsg appendString:@"</soap:Body>"];
[soapMsg appendString:@"</soap:Envelope>"];

I am having this Xml message how to receive firstname and lastname in webservice c#??