1. Install Adobe Digital Editions (ADE) on your PC.
http://www.adobe.com/products/digitaleditions/
2. Plug-in your Nook and allow ADE to activate it.
3. In ADE import the eBook files in the Sony Reader ‘My Books’ Folder. The Folder is at \Documents\My Books\eBook Library.
4. Now drag these eBooks to your Nook.