To get the biggest bang from your Kindle Fire investment, get this book and find out what's missing from Amazon's App Store for Android.
FAST START GUIDE TO KINDLE FIRE
SHOPPING FOR APPS ON YOUR KINDLE FIRE
MUSIC AND VIDEO
SHOP TILL YOU DROP!
EDUCATION AND REFERENCE
PRIORITIZING YOUR APPS
SIDELOADING APPS AND APP STORE ALTERNATIVES
This is a great book if you're entirely new to a Kindle device. Those of us who have ran some sort of smart device within the least 3 years will find this book a bit redundant. Although, to be fair, the blip about sideloading apps is quite useful. I personally have not tried it yet, but that 'chapter' is about the only worth-while part of the book.
If you are new to Kindle (or a smart device in general), it's worth it. Otherwise, just google how to sideload an app.
WOULD RECOMMEND: Only if you're an absolute newbie.