Seems like you've read documentation that isn't endorsed by the original iText developer (being me). May I ask you for the URL where you've found that documentation, so that I can ask for a cease and desist?
As for the answer to your question: please take a look at the official documentation, and you'll find the MyFirstTable example. Based on this example, you can adapt your own code as follows:
var table = new PdfPTable(3);
var cell = new PdfPCell(new Phrase("Cell with colspan 3"));
cell.Colspan = 3;
table.AddCell(cell);
table.AddCell("row 2; cell 1");
table.AddCell("row 2; cell 2");
table.AddCell("row 2; cell 3");
As you can see, there's no reason to use the PdfPRow
class. The PdfPRow
class is used internally by iText, but as documented in my book, developers using iText shouldn't use that class in their code.