How to PrintDocument and check PrintPreview

Drag and drop PrintDocument control, PrintDialog control and PrintPreviewDialog control from the toolbox on the WindowForm.

PrintDocument:  The PrintDocument object encapsulates all the information needed to print a page. They associate with the control which content can be print.  They handle the events and operations of printing.

Step1:      Associate control to Print document

private void printDocument1_PrintPage(object sender, System.Drawing.Printing.PrintPageEventArgs e)
{
           e.Graphics.DrawString(richTextBox1.Text, richTextBox1.Font, Brushes.Black, 100, 20);
           e.Graphics.PageUnit = GraphicsUnit.Inch;           
}

Step2:  write code for printing and print preview.

private void btnPrint_Click(object sender, EventArgs e)
{
            //PrintDialog associate with PrintDocument;
            printDialog1.Document = printDocument1; 
  
            if (printDialog1.ShowDialog()==DialogResult.OK)
            {
                printDocument1.Print();
            }
}
  
private void btnPrintPreview_Click(object sender,  EventArgs e)
{
            //Associate PrintPreviewDialog with PrintDocument.
            printPreviewDialog1.Document = printDocument1;   
   
            // Show PrintPreview Dialog
            printPreviewDialog1.ShowDialog();
}

Run the project

When you click PrintPreview Button then PrintPreview dialog will open.

When click Print Button then Print dialog will open.

When you click Print Button then output will goes to the Printer.