I've installed and tested the application and the only way to print an image on the item is through the Envelope setting available within the File > Page Setup section. When you select Booklet, there is no way to customize the output with the image you want, but when you select Envelope, a field image appears automatically where you can specify the image.
Access the application's page at Software Informer to download the application or if you already have it installed, go to File > Page Setup to see all the available print modes.