How would I implement IDisposable in this context?

I'm using Entity Framework 4 along with MSSQL to store and access data on my Windows Forms application.

Here is an example class I use to access data:

public class StudentRepository : IDisposable
{
    ColegioDBEntities db = new ColegioDBEntities();

    public IQueryable<Student> FindAllStudents()
    {
        return db.Students;
    }

    public Student FindStudent(int id)
    {
        return db.Students.SingleOrDefault(c => c.StudentId == id);
    }

    public void Add(Student Student)
    {
        db.AddToStudents(Student);
    }

    public void Save()
    {
        db.SaveChanges();
    }

    public void Dispose()
    {
        db.Dispose();
    }
}

And here's an example of how I use it.

private void btnLogin_Click(object sender, EventArgs e)
{
    UserRepository repo = new UserRepository();
    var result = repo.FindAllUsers().Where(u => u.Username == txtUsername.Text && u.Password == txtPassword.Text);
    if (result.Count() > 0)
    {
        MainForm form = new MainForm(txtUsername.Text);
        form.Show();
        this.Hide();
    }
    else
    {
        MessageBox.Show("Usuario y/o contraseña incorrecta.",
        "Acceso Denegado",
        MessageBoxButtons.OK,
        MessageBoxIcon.Stop,
        MessageBoxDefaultButton.Button1);
        txtUsername.Focus();
        txtPassword.Focus();
    }
}

Someone suggested that I use IDisposable to properly "clean up" the connection, but I don't know how to implement this.

Any suggestions?

Solution

Not sure if I really got the point, but you seem to implement IDisposable, but you need to call Dispose or use using:

  using(UserRepository repo = new UserRepository())
  {
    // ...
  }

This calls Dispose when leaving the using block and cleans up the UserRepository.

There is some more information: