main.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace LearnTreeDS
{
    public class Node
    {
        public string Name { get; set; }
        public bool Visited { get; set; }
        public List<Node> Children { get; set; } = new List<Node>();
    }

    class Program
    {
        /*
          
                    _ R_
                  /   |  \ 
                 1    2   3
               / | \
              4  5  6
          
          
         */

        public static void TraverseFn(Node currentNode)
        {
            currentNode.Visited = true;
            Console.WriteLine("Visited: " + currentNode.Name);

            foreach (var child in currentNode.Children)
                TraverseFn(child);
        }

        static void Main(string[] args)
        {
            var Root = new Node() { Name = "Root" };
            var child1 = new Node() { Name = "1" };

            child1.Children.Add(new Node() { Name = "4" });
            child1.Children.Add(new Node() { Name = "5" });
            child1.Children.Add(new Node() { Name = "6" });

            Root.Children.Add(child1);
            Root.Children.Add(new Node() { Name = "2" });
            Root.Children.Add(new Node() { Name = "3" });

            TraverseFn(Root);
            Console.ReadLine();
        }
    }
}