Try tapping on your Reader icon, then choosing "Open Book from Storage." Then you can tap "Internal Storage" to get a list of the folders on your PE (internal, anyway). Choose the file that contains your pdfs, probably "download" or "Digital Editions," tap it to open, then tap your pdf to open it with the Reader on the e-ink side. You can add it to the Library if you want from there.
You can do the same thing by opening your Library and choosing Storage from the drop-down menu on the top left.
Have fun!
