Everybody starts out as a noob, and when it comes down to it, we're all noobs about more things than not!
A "launcher" is an app that lets you run other apps. On an android phone, it's what you see when nothing else is open (like when you press the home key). Functionally, it's like your desktop in windows -- doesn't really do anything by itself, but it lets you access all the stuff you do stuff with.
Search the Play store for "
launchers for android", pick one you like, and install that rascal on your Nook.
I assume that since you've already rooted your Nook you know how to transfer and install an APK. I'm still fairly "noo" in that area myself, but you can
find a quick run down here.