How to display a random object in C#

I'm just learning C# and cannot display a random object in an arraylist. Code as follows ` ArrayList emp = new ArrayList(); hseEmployee e3 = new hseEmployee("Aine","Porter",5,26000); hseEmployee e4 = new hseEmployee("Tara", "Standard", 2, 20000); hseEmployee e5 = new hseEmployee("John", "Porter", 7, 28000); hseEmployee e6 = new hseEmployee("Keith", "Porter", 3, 22000); hseEmployee e7 = new hseEmployee("Aine", "Porter", 5, 26000);

        emp.Add(e3);
        emp.Add(e4);
        emp.Add(e5);
        emp.Add(e6);
        emp.Add(e7);

        Doctor d = new Doctor("Niamh","Doctor",5,40000);
        Doctor d1 = new Doctor("Briege", "Doctor", 13, 100000);
        Doctor d2 = new Doctor("Thomas", "Doctor", 9, 60000);
        Doctor d3 = new Doctor("Ciara", "Doctor", 1, 30000);
        Doctor d4 = new Doctor("Chris", "Doctor", 6, 50000);

        emp.Add(d);
        emp.Add(d1);
        emp.Add(d2);
        emp.Add(d3);
        emp.Add(d4);
        for (int i = 0; i <=10; i++)
        {
            Random r = new Random();
            int index = r.Next(emp.Count);
            richTextBox1.AppendText(emp[index].ToString());

        }
    }`