The form data can be sent to an email, a text file (which can be pasted into Excel or a CSV file), or both.
First, open the page which contains the form in SiteBuilder and click on the Submit button for the form. Look to the right and you'll see the option to send the data to email, text file, or both. Select one of the text file options, save & publish.
To retrieve the data after someone has submitted a form, log into your account, and click the Websites manager link on the left side of the page. Choose the relevant site from the dropdown menu > click More > click Manage Forms and you will see a window with the text files. You can select the check box on the left side of the file name, and click View. When the file opens, you can copy & paste the data into a spreadsheet.