Importing an existing PDF does not create an HTML form, it allows you to use FormsCentral to collect and analyze the responses for an existing PDF, but does not give you a URL or create an HTML form.
If you want to have an HTML form you would have to create it from scratch or by editing one of the Templates.
Here is a brief tutorial of the Import PDF feature: http://tv.adobe.com/watch/acrobat-xi-tips-tricks/how-to-import-a-pdf-form-into-formscentra l/
Thank you Josh. One more question for ya:
If we create new HTML forms, and after someone completes and submits the form, will we be able to view the completed forms in PDF format?
Yes - one of the features in the paid account is saving the response as PDF, a PDF that looks like the original form filled out.
Something useful, when authoring your form in FormCentral there is a view setting at the bottom right corner of the Design tab for "Web View" and "Page View", you can make changes in Page view specifically for the PDF like adding page breaks that are unique from the page breaks added in Web view. I hope that is not too confusing but it is useful in designing a form that looks good in both HTML and PDF.