using System;

public class Program

{

    public static void Main()

    {

        var nomes = new Names[2]; 

        nomes[0] = new Names {  FirstName = "Pedro" };

        nomes[1] = new Names {  FirstName = "Joaquim", LastName = "Soares" } ;

        nomes[0].LastName = "Barbosa";

        Console.WriteLine(nomes[0].FullName);

        Console.WriteLine(nomes[1].FullName);

    }

}

​

class Names

{

    public string FirstName { get; set; }

    public string LastName { get; set; }

    public string FullName { get {return FirstName + " " + LastName; } }

}