I wrote the article Introduction to Web Site Scraping but most of that is not useful here.
See Html Agility pack. The responses to asp.net - Find div at run time at server side in c# - Stack Overflow indicate it can be used in C# in ASP.Net. You can fiddle with it in a console program in [Fork] Web Scraping using HtmlAgilityPack | C# Online Compiler | .NET Fiddle]4.