How to replace strings in a List

I got values from a .csv file and put them into a datagridview, but I'd like to replace some values before to fill my datagridview.

This is the screen of my .csv file:

and this is my code to try to do it:

string FileName = @"C:\mydir\testcsv.csv";
    OleDbConnection conn = new OleDbConnection
           ("Provider=Microsoft.Jet.OleDb.4.0; Data Source = " +
             Path.GetDirectoryName(FileName) +
             "; Extended Properties = \"Text;HDR=YES;FMT=Delimited\"");

    conn.Open();

    OleDbDataAdapter adapter = new OleDbDataAdapter
           ("SELECT * FROM " + Path.GetFileName(FileName), conn);

    DataSet ds = new DataSet("Temp");
    adapter.Fill(ds);

    conn.Close();

    DataTable dt = ds.Tables[0];

    List<HT> matchhtList = new List<HT>();
    matchhtList = (from DataRow dr in dt.Rows
                   select new HT()
                   {
                       Home = dr["Home"].ToString(),
                       Away = dr["Away"].ToString(),
                       ScoreHome = dr["ScoreHome"].ToString(),
                       ScoreAway = dr["ScoreAway"].ToString(),
                       Segno = dr["Segno"].ToString(),
                       odd1 = dr["odd1"].ToString(),
                       oddx = dr["oddx"].ToString(),
                       odd2 = dr["odd2"].ToString()

                   }).ToList();

    StringBuilder mystring = new StringBuilder("matchhtList");
    mystring = mystring.Replace("Rosenborg", "Rihanna")
           .Replace("Start", "Stop")
           .Replace("Brann", "Circus");

    dataGridView2.DataSource = mystring;

Please, if my question is not clear, tell me before to put "-1", I'll try to explain better my question. Thank you very much!