Is there a way to create my own theme by uploading a new background image?

Is there a way to create my own "theme" by uploading a background photo? I just received the email with the spring themes and I have a similar photo that I use on all of my materials that I would love to incorporate.

Thank you!

Yes, you can create or change things within themes or make new ones from scratch.

See https://www.jotform.com/help/184-How-to-Use-Your-JotForm-Themes to get a better understanding of using form themes.

Basically how it works is you first create a form with some form fields then customized further with the form designer and also by using customized css.

So for instance if you just want to change the background to a different picture as you've mentioned above all you need to do is get that theme you like then open it in the form designer and select the background images tab and choose a background image or upload your own to use.