It won't be as simple as that. You can submit a form to a web server, which could read the data and add it to a spreadsheet, but this would require you to program the web server (e.g., using PHP, Perl, ASP, etc.) to do this. The form would submit to this server-side program (script), as opposed to the file as you're currently attempting to do.
If you use Acrobat to distribute the form and collect the responses in Tracker, it can export the results to a CSV or XML file, which can be placed into a spreadsheet.
