What is JotForm?
JotForm is a free online form builder which helps you create online forms without writing a single line of code. No sign-up required.
At JotForm, we want to make sure that you’re getting the online form builder help that you need. Our friendly customer support team is available 24/7.
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.
I'm afraid you cannot use a PDF file as the background of your form, because a background can be set only with an image.
Can you please describe in more detail what you may be trying to achieve?
If it is to simply display a PDF file that you already have, you can use our PDF Embedder widget:
If it is something else instead, please describe what it is you may be trying to achieve in more details, and we'll be happy to look for ways how it could be accomplished. Thank you.