The following code snippet shows how to print text in WPF.

private void PrintSimpleTextButton_Click(object sender, RoutedEventArgs e)
{

    // Create a PrintDialog
    PrintDialog printDlg = new PrintDialog();

    // Create a FlowDocument dynamically.
    FlowDocument doc = CreateFlowDocument();
    doc.Name = "FlowDoc";

    // Create IDocumentPaginatorSource from FlowDocument
    IDocumentPaginatorSource idpSource = doc;

    // Call PrintDocument method to send document to printer
    printDlg.PrintDocument(idpSource.DocumentPaginator, "Hello WPF Printing.");           

}

private FlowDocument CreateFlowDocument()
{

    // Create a FlowDocument
    FlowDocument doc = new FlowDocument();

    // Create a Section
    Section sec = new Section();

    // Create first Paragraph
    Paragraph p1 = new Paragraph();

    // Create and add a new Bold, Italic and Underline
    Bold bld = new Bold();
    bld.Inlines.Add(new Run("First Paragraph"));
    Italic italicBld = new Italic();
    italicBld.Inlines.Add(bld);
    Underline underlineItalicBld = new Underline();
    underlineItalicBld.Inlines.Add(italicBld);

    // Add Bold, Italic, Underline to Paragraph
    p1.Inlines.Add(underlineItalicBld);

    // Add Paragraph to Section
    sec.Blocks.Add(p1);

    // Add Section to FlowDocument
    doc.Blocks.Add(sec);

    return doc;

}