Не создается объект класса - C#

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
 
namespace ConsoleApplication3
{
    class Book
    {
        string name;
        string avtor;
        string ganr;
        int years;
        public string Name
        {
            get
            {
                return name;
            }
            set {
                name = value;
            }
       }
        public string Avtor
        {
            get
            {
                return avtor;
            }
            set
            {
                avtor = value;
            }
        }
        public string Ganr
        {
            get
            {
                return ganr;
            }
            set
            {
                ganr = value;
            }
        }
        public int Years
        {
            get
            {
                return years;
            }
            set
            {
                years = value;
            }
        }
    }
    class Library {
        Book[] books;
        public Library()
        {
            books = new Book[10];
        }
        public void add_book(string name, string avtor, string ganr, int years)
        {
            this.books[0].Name = name;
            this.books[0].Avtor = avtor;
            this.books[0].Ganr = ganr;
            this.books[0].Years = years;
                ////books[books.Length-1].Name = Console.ReadLine();
                ////books[books.Length-1].Avtor = Console.ReadLine();
                ////books[books.Length-1].Ganr = Console.ReadLine();
                //books[0].Years = Convert.ToInt32(Console.ReadLine());
        }
        public int find_name(string name)
        {
            for (int i = 0; i < books.Length; i++)
            {
                if (books[i].Name == name) return i;
            }
            return -1;
        }
        public int find_avtor(string avtor)
        {
            for (int i = 0; i < books.Length; i++)
            {
                if (books[i].Avtor == avtor) return i;
            }
            return -1;
        }
        public int find_ganr(string ganr)
        {
            for (int i = 0; i < books.Length; i++)
            {
                if (books[i].Ganr == ganr) return i;
            }
            return -1;
        }
        public int find_avtor(int years)
        {
            for (int i = 0; i < books.Length; i++)
            {
                if (books[i].Years == years) return i;
            }
            return -1;
        }
        public void print(int pos) {
            books[pos].Name = Console.ReadLine();
            books[pos].Avtor = Console.ReadLine();
            books[pos].Ganr = Console.ReadLine();
            books[pos].Years = Convert.ToInt32(Console.ReadLine());
        }
        public int get_length() {
            return books.Length;
        }
    }
    class Program
    {
        static void Main(string[] args)
        {
            Library l = new Library();
            Console.WriteLine("1    - Add book");
            Console.WriteLine("2    - Delete book");
            Console.WriteLine("3    - Find name");
            Console.WriteLine("4    - Find avtor");
            Console.WriteLine("5    - Find ganr");
            Console.WriteLine("6    - Find years");
            Console.WriteLine("7    - Print");
            Console.WriteLine("8    - Exit");
            int change = 0;
            //int k;
            //int pos;
            while (change != 8)
            {
                change = Convert.ToInt32(Console.ReadLine());
                switch (change)
                {
                    case 1:
                        l.add_book("petr", "pako", "comedy", 1987);
                        break;
                    case 2:
                      
                        break;
                    case 3:
                        
                        break;
                    case 4:
                        
                        break;
                    case 5:
                        
                        break;
                    case 6:
                        
                        break;
                    case 7:
                        for(int i = 0; i < l.get_length(); i++){
                            l.print(i);
                        }
                        break;
                    case 8:
 
                        break;
                }
            }
        }
    }
}