three tire architecture problem

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C#

ASP.NET

please guys help me i am using three tire architecture
and i am using dataset
i am showing
step one (Contract Class Library )

public class Authentication
    {
        public Guid ID { get; set; }
        public string UserName { get; set; }
        public string Name { get; set; }
        public string Password { get; set; }
        public Char? Role { get; set; }
    }

Step two (Data Class Library)
where i used interface and data class

public interface IAuthenticationRepository
    {
   DataSet  SaveAuthentication(KENTCRM.Contract.AuthenticationobjAuthentication);
    }

and

public class AuthenticationRepository:IAuthenticationRepository,IDisposable
   {
      public DataSet SaveAuthentication(KENTCRM.Contract.Authentication objAuthentication)
      {
          DataSet dt = new DataSet();
          return dt;
      }

Three Step is Business class Library

public DataSet SaveAuthentication(KENTCRM.Contract.Authentication objAuthentication)
      {
          using (AuthenticationRepository obj = new AuthenticationRepository())
          {
             return obj.SaveAuthentication(objAuthentication);
          }
      }

this is my architecture
but i am not able to use business class please check and help me . how i can use business call and what is the right way
if it is possible so show me right architecture with data set
i want to create login page and insert ,update and delete

[edit]Code blocks added - OriginalGriff[/edit]