I want to collect all tags in from this div but do not know how to do this in the best way with xpath method
HtmlDocument html = new HtmlDocument();
html.Load(new StringReader(result));
var anchorTags = html.DocumentNode.SelectNodes("//div[@class='biz_info']//a")
.Select(a => a.OuterHtml)
.ToList();
That will give you list of anchor tags html. If you need just urls:
urls = html.DocumentNode.SelectNodes("//div[@class='biz_info']//a[@href!='']")
.Select(a => a.Attributes["href"].Value)
.ToList();