In this demo you can learn how to load a PDF document with a form, enter some values from code and then save the modified PDF document.

After the PDF document was loaded you can iterate the fields in the Document.Form.Fields collection or you can get a field from collection by index or by name.
PDF Document with Form to Fill
Open
Enter the Form Fields Values
Text Box Field Text:
List Box Field Value:
Combo Box Field Value:
Selected Radio Button: