If you wish to sideload content from your Mac to your NOOK, you will be required to download Android File Transfer. Android File Transfer is an application for Macintosh computers (running Mac OS X 10.5 or later) you can use to view and transfer files between your Mac and an Android device (running Android 3.0 or later).
2. Drag the Android icon to the Applications folder
3. Connect your NOOK to your Mac
4. Open Android File Transfer from the Applications folder
This will display your MyNOOK drive.
Drag and drop any files that you wish to sideload into the appropriate sub-folder in the My Files folder.
NOTE: If the NOOK device is not appearing on the Mac desktop, try switching from MTP to PTP mode in the NOOK Settings menu (MTP not supported by Mac).