How to manually add nodes to Link List C#

Question

I've made a Link List program in C# which creates a link list of 10 random nodes. But instead I want to manually enter the numbers myself. I'm not sure how to add a function so that I can manually add the numbers myself when the program runs rather than having them random generated? I've tried the code below but it doesn't seem to work. Any help would be appreciated

namespace Linked_List
{
class Program
{

    public static void Main(String[] args)
    {
        Console.WriteLine("Linked List: ");
        int size = 10;
        int[] a;

        a = new int[size + 1];

        for (int i = 1; i <= size; i++)

        {
            Console.WriteLine("What value do you want to add?");
            a[i] = Convert.ToInt32(Console.ReadLine());
            Node n = new Node(a[i]);


            Node head = List(a, n);
            print_nodes(head); //used to print the values
            Console.ReadLine();
        }

    }
    public class Node
    {
        public int data;
        public Node next;
    };

    static Node add(Node head, int data) //Add nodes
    {
        Node temp = new Node();
        Node current;
        temp.data = data;
        temp.next = null; //next point will be null

        if (head == null) // if head is null
            head = temp;
        else
        {
            current = head;
            while (current.next != null)
                current = current.next;
            current.next = temp; //links to new node
        }
        return head;
    }

    static void print_nodes(Node head) //print the values in list
    {
        while (head != null) //while head is not null
        {
            Console.Write(head.data + " "); //outputs the numbers
            head = head.next;
        }
    }

    static Node List(int[] a, int n)
    {
        Node head = null; //head is originally null
        for (int i = 1; i <= n; i++)
            head = add(head, a[i]);
        return head;
    }

   
}
}

Answer 1

This will ask you to out in the values manually

public static void Main(String[] args)
{
    Console.WriteLine("Linked List: ");
    int n = 10;
    Random r = new Random(); 
    int[] a;
    a = new int[n + 1];

    for (int i = 1; i <= n; i++)
        a[i] = int.Parse(Console.ReadLine()); // here, no extra class needed

    Node head = List(a, n);
    print_nodes(head); 
    Console.ReadLine();
}