Thank you to Duke University for graciously allowing re-use of some of the content from their guide.
Many ebooks are provided in pdf format. This is not, however, always the ideal file type to use on an ereader as you cannot adjust the size of the font or always, in the case of the Nook Color, go from page to page easily. A solution for both issues is to convert your pdf to EPUB.
To convert documents to epub or a Kindle format , use Calibre -- an open source freely available ebook management program available for Windows, Mac and Linux. Download it here: http://calibre-ebook.com/.
On a Nook or other DRM enabled ereader:
Once the book is in Adobe Digital Editions :
For non-downloadable books, you may create PDF files of the chapters/page ranges you want to read and transfer them to your nook.