HtmlAgilityPackHelper is a static class which allows you to Parse Site HTML for Data

HtmlAgilityPackHelper.cs

using System;
using System.Collections.Generic;
using HtmlAgilityPack;
using digioz.BO;

namespace digioz.BLL
{
    public static class HtmlAgilityPackHelper
    {
        /// <summary>
        /// Method to Get an HTML Document
        /// either a remote one from a URL 
        /// or based on an HTML String Passed in
        /// as a parameter to the function
        /// </summary>
        /// <param name="url"></param>
        /// <param name="htmlString"></param>
        /// <returns></returns>
        public static HtmlDocument GetDocument(string url = "", string htmlString = "")
        {
            var getHtmlWeb = new HtmlWeb();
            HtmlDocument document = new HtmlDocument();

            if (htmlString == "")
            {
                document = getHtmlWeb.Load(url);
            }
            else
            {
                document.LoadHtml(htmlString);
            }

            return document;
        }

        /// <summary>
        /// Method to get the InnerHTML of an HTML 
        /// Code Block based on the specified Id
        /// </summary>
        /// <param name="url"></param>
        /// <param name="id"></param>
        /// <returns></returns>
        public static string GetHtmlById(string id, string url = "",  string htmlString = "")
        {
            var getHtmlWeb = new HtmlWeb();
            var document = GetDocument(url);
            var innerHtml = document.GetElementbyId(id).InnerHtml;

            return innerHtml.ToString();
        }

        /// <summary>
        /// Method to retrieve a list of URLs 
        /// along with the Hyperlink Text based
        /// on a pre-specified filtering criteria
        /// </summary>
        /// <param name="url"></param>
        /// <param name="filter"></param>
        /// <param name="htmlString"></param>
        /// <returns></returns>
        public static List<Link> GetLinks(string url = "", string filter = "", string htmlString = "")
        {
            List<Link> links = new List<Link>();
            var getHtmlWeb = new HtmlWeb();
            HtmlDocument document = null;

            document = GetDocument(url, htmlString);

            var aTags = document.DocumentNode.SelectNodes("//a");

            if (aTags != null)
            {
                foreach (var aTag in aTags)
                {
                    Link link = new Link
                    {
                        Text = aTag.InnerHtml,
                        Url = aTag.Attributes["href"].Value
                    };

                    if (filter.Length > 0)
                    {
                        if (link.Url.Contains(filter))
                        {
                            links.Add(link);
                        }
                    }
                    else
                    {
                        links.Add(link);
                    }
                }
            }

            return links;
        }

    }
}

Link.cs

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

namespace digioz.BO
{
    public class Link
    {
        public string Text { get; set; }
        public string Url { get; set; }
    }
}