...
// add a table to the report container
SubItemTable table = new SubItemTable(container.SubItems);

// add new data and header lines to this table
TableLineData tableLineData = new TableLineData(table.Lines.Data);
TableLineHeader tableLineHeader = new TableLineHeader(table.Lines.Header);

// add a field to the header line
TableFieldText header = new TableFieldText(tableLineHeader.Fields);
header.Contents = "\"head\"";
...