JotForm is a free online form builder which helps you create online forms without writing a single line of code. No sign-up required.
We believe that if one user has a question, there could be more users who may have the same question. This is why many of our support forum threads are public and available to be searched and viewed. If you’d like help immediately, feel free to search for a similar question, or submit your question or concern.
Are you referring on connecting to a Google Spreadsheet?
If you are, you cannot connect an existing spreadsheet to it, BUT you can integrate Google Spreadsheet, when you integrate it will allow you to create a new spreadsheet in your Google Drive. Here's the guide on that: http://www.jotform.com/help/228-How-to-Integrate-Form-with-Google-Spreadsheet.
Do let us know if I have misunderstood your concern.