HttpWebRequest httpWebRequest = WebRequest.Create(@"http://www.cnblogs.com") as HttpWebRequest;
        HttpWebResponse httpWebResponse = httpWebRequest.GetResponse() as HttpWebResponse;
        Stream stream = httpWebResponse.GetResponseStream();
        StreamReader reader = new StreamReader(stream, Encoding.UTF8);
        string s = reader.ReadToEnd();
        reader.Close();
        stream.Close();
        httpWebResponse.Close();
        HtmlDocument htmlDoc = new HtmlDocument();
        htmlDoc.LoadHtml(s);
        HtmlNodeCollection anchors = htmlDoc.DocumentNode.SelectNodes(@"//a[@class='titlelnk']");
        foreach (HtmlNode anchor in anchors)
            Console.WritleLine(anchor.InnerHtml);

------解决方案--------------------

a.下载网页数据;
b.处理网页得到想要的数据;
c.保存数据

对于a有三种方式
1.使用WebClient下载  2.使用HttpWebRequest和HttpWebResponse 3.使用WebBrowser

对于b
1.正则表达式匹配; 2.使用HtmlAgilityPack

对于c  按个人需求而定