Select the Laptop/Desktop choice and click "Continue".
For step 2, if you successfully downloaded and installed Adobe Digital Editions on your computer click "Done with this step".
Select your download period and download format and click "Download Your Book".
Still on your computer, open Adobe Digital Editions.
Attach your Kindle Fire to your computer via USB cable. Your Kindle should now say, "You can now transfer files from your computer to Kindle." (If it does not, try unplugging and plugging the cable back in.)
You should see a Kindle device in the bottom left pane of the Adobe Digital Editions window.
When prompted, authorize your Kindle.
Drag and drop your book from Adobe Digital Editions Library to your Kindle.
Unplug your Kindle.
Open the Bluefire Reader app on your Kindle, you should see your downloaded book listed.