You can also change the Splash Screen "Wallpaper" on a Stock Unrooted Kindle Fire. The advantages are, It is more stable and you do not void your warranty,
You, with the help of a Droid Cell Phone, have the full availability of GooglePlay, where you can get any Android App that they have, d/l to your phone and then sideload it into your Kindle Fire.
This is my Lock Screen
This is my Home Screen.