To add an image to a form, you'll need the image's URL.

If you haven't worked with Image URLs before, please see: What's an Image URL? How do I get one?

Once you have the Image URL:

1. In the form editor, click Add Field.
2. From the field type selector, choose 'Image'. It'll be in the Informative Fields section.
3. Paste the Image URL in the light-yellow box.
4. Click Done.