Having problems with this code

using System; class EmployeesReadOnlyDemo { static void Main() {

Employee myAssistant = new Employee(1234); Employee myDriver = new Employee(2345); Employee myAssistant Employee IdNumber = 3456; } } class Employee { private readonly int idNumber; public Employee(int id) { () idNumber = id; } public interface IdNumber { AttributeTargets IdNumber.Employee(IdNumber.IdNumber); } set {

idNumber = value; } } }