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.
Yes, it is asking for source, because you need to copy and paste the URL of the image on the "Source" field.
For example, following image's URL is "http://firstname.lastname@example.org?3.3.9969". When you click to that URL, you will be redirected to that image.
Also, if the image on the web source, you can easily get the URL of the image by right clicking, then selecting the "Copy image URL" option.
After that you can paste this URL to the "Source" field in the "Insert/edit Image" on the "Autoresponder"'s template. If you still have some questions, please let us know.