Adobe ACROBAT READER 7.0 Manual page 248

Adding Adobe PDF documents to My Digital Editions
You can also add PDF documents to the My Digital Editions bookshelf. For example, you
might want to include technical papers in Adobe PDF in your library. You can open and
manage these PDF documents in the same way as you open and manage Digital Editions.
To add a PDF document to the My Digital Editions bookshelf:
1. In My Digital Editions, click Add File.
2. In the Add File dialog box, locate and select the PDF document, and then click Add.