'test datatable
        Dim dt As New DataTable
        dt.Columns.Add("col1")
        dt.Columns.Add("col2")

        'add new row
        Dim dr As DataRow
        dr = dt.NewRow()
        dr.Item(0) = "row1col1"
        dr.Item(1) = "row1col2"
        dt.Rows.Add(dr)

        'add dynamic column
        dt.Columns.Add("col3")

        'add value to column
        dr.Item(2) = "row1col3"