Display exception with RestSharp using C# in ASP.Net

Hi

I have below code & i want if successfully done then Success message should get displayed else if there i.e. error or Awb no does not exists then it should show some message

var client = new RestClient("api.nimbuspost.com/v1/shipments/cancel");
client.Timeout = -1;
var request = new RestRequest(Method.POST);
request.AddHeader("Content-Type", "application/json");
 
var body = @"{" + "\n" +
@"    ""email"" : ""r2@gmail.com""," + "\n" +
@"    ""password"" : ""T!""" + "\n" +
@"awb : " + awb + " \n" +
@"}";
request.AddHeader("Authorization", "Bearer " + token);
request.AddParameter("application/json", body, ParameterType.RequestBody);
IRestResponse response = client.Execute(request);