HTML source string Manipulation

Ok so I am getting the Source of the page into a string. What I am wanting to do is manipulate the string so that I am able to pull just a certain table out of the source. How would you recommend I do this? Here is the code I have to get the string of the HTML code.

Code:

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                        WebClient webClient = new WebClient();
                        const string strUrl = "http://www.yahoo.com/";
                        byte[] reqHTML;
                        reqHTML = webClient.DownloadData(strUrl);
                        UTF8Encoding objUTF8 = new UTF8Encoding();
                        objUTF8.GetString(reqHTML); //this returns the HTML of the page

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