// A paragraph with sample text will serve as table content.
Paragraph tableText = new Paragraph(new Run("A bit of text content..."));

Table sampleTable = new Table();

// Create and add a couple of columns.
sampleTable.Columns.Add(new TableColumn());
sampleTable.Columns.Add(new TableColumn());

// Create and add a row group and a couple of rows.
sampleTable.RowGroups.Add(new TableRowGroup());
sampleTable.RowGroups[0].Rows.Add(new TableRow());
sampleTable.RowGroups[0].Rows.Add(new TableRow());

// Create four cells initialized with the sample text paragraph.
sampleTable.RowGroups[0].Rows[0].Cells.Add(new TableCell(tableText));
sampleTable.RowGroups[0].Rows[0].Cells.Add(new TableCell(tableText));
sampleTable.RowGroups[0].Rows[1].Cells.Add(new TableCell(tableText));
sampleTable.RowGroups[0].Rows[1].Cells.Add(new TableCell(tableText));

// Finally, use the FlowDocument constructor to create a new FlowDocument containing 
// the table constructed above.
FlowDocument flowDoc = new FlowDocument(sampleTable);