Attempting to create an infinite scroll app using jquery and asp.net

I am attempting to create an infinite scroll app using asp.net and jquery.  I would like it to be able to pull 10 records at a time.  I did in fact find a somewhat half done solution but it keeps repeating the same information from an xml source.  Does anybody have an idea on how I can do this as a commenting system similar to facebook?  This is the code that I found in the default.aspx.cs file.  How could I make it so that I am only pulling 10 records per postback?

     [WebMethod]
        public static string Foo()
        {
            StringBuilder getPostsText = new StringBuilder();
            using (DataSet ds = new DataSet())
            {
                ds.ReadXml(HttpContext.Current.Server.MapPath("App_Data/books.xml"));
                DataView dv = ds.Tables[0].DefaultView;

                foreach (DataRowView myDataRow in dv)
                {
                    getPostsText.AppendFormat("<p><b>author:</b> {0}</br>", myDataRow["author"]);
                    getPostsText.AppendFormat("genre: {0}</br>", myDataRow["genre"]);
                    getPostsText.AppendFormat("price: {0}</br>", myDataRow["price"]);
                    getPostsText.AppendFormat("publish date: {0}</br>", myDataRow["publish_date"]);
                    getPostsText.AppendFormat("description: {0}</br></p>", myDataRow["description"]);
                }
                getPostsText.AppendFormat("<div style='height:15px;'></div>");

            }
            return getPostsText.ToString();
        }