Unfortunately you will need to learn about DRM (Digital Rights Management) as it
relates to ebook formats. Also the PDF format is not a good one to use on small
screen black & white displays. The regular Jetbook has no DRM support and the
Jetbook Lite only has support for the eReader PDB DRM.
To make use of books purchased from the a site like eBooks.com you will need
to learn how to remove the DRM. There are a number of sources for free
non-DRM ebooks. Try a Google of "non-DRM ebooks"