how to mark read and unread row in gridview in asp.net plese help...

string strMyContion = "";
        protected void gvFiles_RowDataBound(object sender, GridViewRowEventArgs e)
        {
            if (e.Row.RowType == DataControlRowType.DataRow)
            {
                GridViewRow gvr = e.Row;
 
                if (strMyContion satisfies with the row i want)
                {
                    // To Mark 
                    gvr.ForeColor = System.Drawing.Color.Red;
 
                    // To Read 
                    string col1Value = gvr.Cells[0].Text;
                    Label lblTestValue = (Label)gvr.FindControl("lblTest");
 
                    // To Write 
                    gvr.Cells[0].Text = "CellData_Modified";
                    ((Label)gvr.FindControl("lblTest")).Text = "Label_Test";
                    ((TextBox)gvr.FindControl("txtDataTest")).Text = "TextBox_Test";
                }