Insert node at beginning of doubly linked list in c#

Csharp program for Insert node at beginning of doubly linked list. Here problem description and explanation.

// Include namespace system
using System;
// Csharp Program For
// insert new node at beginning of doubly linked list

// Define class of linked list Node
public class LinkNode
{
	public int data;
	public LinkNode next;
	public LinkNode prev;
	public LinkNode(int data)
	{
		this.data = data;
		this.next = null;
		this.prev = null;
	}
}
public class DoublyLinkedList
{
	public LinkNode head;
	public DoublyLinkedList()
	{
		// Set inital value
		this.head = null;
	}
	// Insert new node at beginning position
	public void insert(int value)
	{
		// Create a node
		var node = new LinkNode(value);
		node.next = this.head;
		// When linked list is not empty
		if (this.head != null)
		{
			this.head.prev = node;
		}
		// Make new head
		this.head = node;
	}
	// Display node element of doubly linked list
	public void display()
	{
		if (this.head == null)
		{
			Console.WriteLine("Empty Linked List");
		}
		else
		{
			Console.WriteLine("  Doubly Linked List Element :");
			// Get first node of linked list
			var temp = this.head;
			// iterate linked list 
			while (temp != null)
			{
				// Display node value
				Console.Write("  " + temp.data.ToString());
				// Visit to next node
				temp = temp.next;
			}
		}
	}
	public static void Main(String[] args)
	{
		var dll = new DoublyLinkedList();
		// Insert following linked list nodes
		dll.insert(70);
		dll.insert(60);
		dll.insert(50);
		dll.insert(40);
		dll.insert(30);
		dll.insert(20);
		dll.insert(10);
		//  NULL <- 10 <--> 20 <--> 30 <--> 40 <--> 50 <--> 60 <--> 70->NULL
		dll.display();
	}
}

Output

  Doubly Linked List Element :
  10  20  30  40  50  60  70