How to create and maintain a data file from form inputs?

Data can be exported to PDF or Excel/CSV format from the submission page:

https://www.jotform.com/help/269-How-to-View-Form-Submissions

If you want an online document that is updated with each new submission, it is possible to integrate the form with a Google Docs spreadsheet:

https://www.jotform.com/help/228-How-to-Integrate-Form-with-Google-Spreadsheet