To continue downloading your selected eBook onto your Kindle via USB cable, follow the following steps. Once in the Bookshelf screen, click Download.
Once you’ve selected “Confirm and Download” your browser should take you to Amazon.com. Scroll through the list of options and select “Transfer via Computer”.
With both the Kindle’s Documents and the computer’s Downloads folders open, drag the eBook file from your computer into the Kindle Documents. It should then appear as the last item within this folder.
Eject your Kindle by right clicking- eject. The eBook should now appear on the home screen of your Kindle eReader. You may have to synchronize or check the wireless connection if the book does not display promptly.