This way
protected void Page_Load(object sender, EventArgs e)
{
    DataSet ds = new DataSet();
    ds.Tables.Add(new DataTable());
    ds.Tables[0].Columns.AddRange(new DataColumn[3] { new DataColumn("Id", typeof(int)),
                        new DataColumn("Name", typeof(string)),
                        new DataColumn("Country",typeof(string)) });
    ds.Tables[0].Rows.Add(1, "John Hammond", "United States");
    ds.Tables[0].Rows.Add(2, "Mudassar Khan", "India");
    ds.Tables[0].Rows.Add(3, "Suzanne Mathews", "France");
    ds.Tables[0].Rows.Add(4, "Robert Schidner", "Russia");
    DataTable dt = ds.Tables[0].Select("Name LIKE 'Rob%'").CopyToDataTable();
}