How do you add a cover image after the form has been created?

Hello formsonline,

I am not sure if I have understood your question correctly. 

Do you mean to say that you want to set an image as your form's background? If yes, then it is possible to achieve your requirement by injecting the following custom css code in your form:

.form-all {

background: url(YOUR IMAGE FILE URL) no-repeat top left;

}

The following guide should help you in injecting the custom css code:  http://www.jotform.com/help/117-How-to-Inject-Custom-CSS-Codes 

Hope this helps.

Do get back to us if you meant to ask something else.

Thank you!