[Zope] How to create a file from a form?

Hi All, I'm trying to create a DTML Document, or a DTML Method or a text file from an input form in a web page. I have a form with some input text, some checkboxes and radiobutton and a submit. On submit I have to create a text file and append some text at the end of that file. I can use the manage_addDTMLDocument method to create that file, even if I would create a text file, and not a DTML Document, but I dont know how to append any text at the end of the file or how to edit the file. Can Anyone Help Me? Thanx