How do I access pdfs created in an app to email them? The Yahoo account and iPad don't get along. The Yahoo app only attaches pictures.

I have a class for preschool computer literacy, we created stories in Picturebook. Only one of the iPads functions with the Yahoo mail account, the rest can't connect with the outbox server. I downloaded the Yahoo Mail app, but can only attach pictures. The PDFs of the stories don't show up in the DCIM file, so I can't transfer them to another device to mail them from there. Any suggestions how to pry the files out of the hands of the iPads?