If I want to put a photograph on a post or page I can do this by adding the image (JPG) from the WordPress Dashboard media. If I then want that image (JPG) to be linked to another file (PDF) I replace the JPG image’s URL with the URL of the PDF. Then when the post or page is published a viewer can either click or tap on the published JPG and the linked PDF file opens.
I do not seem to be able to do the same thing using Nextgen Gallery, especially if I upload more than one JPG because only the first JPG shows on the post or page before it is published thus preventing me from using the edit bar link ikon. Also, the Nextgen Gallery does not allow me to upload PDF files.
Thank you for helping.