private void TablesAndCells( string file, int tableIndex )
    {
      using( var document = DocX.Load( file ) )
      {
        // Get the table to modify
        var table = document.Tables[ tableIndex ];

        // Merge the first 3 cells of the first row
        table.Rows[ 0 ].MergeCells( 0, 3 );

        // Merged the last 2 cells in the third row
        var columnCount = table.Rows[ 1 ].ColumnCount;
        table.Rows[ 2 ].MergeCells( columnCount - 2, columnCount - 1 );

        // Merge the first cell of rows 2 and 3
        table.MergeCellsInColumn( 0, 1, 2 );

        // Save the changes to the document
        document.Save();
      }
    }