How to make a class heir?

Question

C++ / C#

It is not possible to make a class heir:

// Сводка:
//     Provides the APIs for managing user in a persistence store.
//
// Параметры типа:
//   TUser:
//     The type encapsulating a user.
public class UserManager<TUser> : IDisposable where TUser : class
{
}

What am I doing wrong?

public class UserManagerWrapper<TUser> : UserManager<TUser>
{

}

Answer 1

public class UserManager<TUser> : IDisposable 
    where TUser : class
{
   public void Dispose()
   {
      throw new NotImplementedException();
   }
}

public class UserManagerWrapper<TUser> : UserManager<TUser> 
    where TUser : class
{

}

Inheriting from UserManager, the new TUser (from UserManagerWrapper) must fulfill the same conditions as the TUser inside the UserManager