Non generic class

Question

This program is producing run time error. How can non generic be implemented in this program. Problem is highlighted

using System;

namespace _6e13
{
class Program
{
static void Main(string[] args)
{
Friend[] friend = new Friend[3];

for (int x = 0; x < friend.Length; ++x)
{
friend[x] = new Friend();

Console.Write("Friend's Name ");
friend[x].name = Console.ReadLine();

Console.Write("Friend's Phone No ");
friend[x].pNo = int.Parse(Console.ReadLine());

Console.Write("Friend's DOB mm/dd/yyyy ");
friend[x].bDay = Console.ReadLine();

Console.WriteLine();
}
Console.WriteLine("\n{0, -15} {1, -18} {2, -20}", "Name", "Phone No", "DOB (mm/dd/yyyy)");
Console.WriteLine("{0, -15} {1, -18} {2, -20}", "====", "========", "================");

Console.WriteLine("\nBefore Sort");

for (int x = 0; x < friend.Length; ++x)
Console.WriteLine("{0, -15} {1, -18} {2, -20}", friend[x].name, friend[x].pNo, friend[x].bDay);

Array.Sort(friend);

Console.WriteLine("\nAfter Sort");

for (int x = 0; x < friend.Length; ++x)
Console.WriteLine("{0, -15} {1, -18} {2, -20}", friend[x].name, friend[x].pNo, friend[x].bDay);

Console.ReadKey();
}
}
}
class Friend
{
public string name { get; set; }
public int pNo { get; set; }
public string bDay { get; set; }

public int CompareTo(object o)
{
if (o is Friend)
{
Friend firstName = (Friend)o;
return string.Compare(this.name, firstName.name);
}
else
throw new ArgumentException("Object is not a Employee.");
}
}