Let's address this step by step.
First: For Windows 8.
Do you know how to get to the Start Screen. The first screen that has all those square tiles you can touch?
Note: You should be able to get to it by pressing the Windows key on your keyboard.
Well, go to that.
Then, look for a tile that shows a shopping bag/bag and says 'Store'. Click on it.
Now tap on 'Top Free Apps'.
That will show a page of apps. IN the list look for apps named 'Windows 8 Tricks' and Windows 8 Tips. There are a few free apps that have advice on how to use Windows 8.
After they are installed (I'd recommend installing at least 2 or 3 free windows 8 tips and tricks apps) press the Windows key on your keyboard again.
Then scroll the main screen until you see the square tile or rectnalge tile for these 'help for Windows 8' apps. now just read them. They explain the main things you should know well.
Second: For ADE.
FIRST, BEFORE anything else, you have to activate your Nook HD for reading library books.
Do the following:
1) Make sure you have the Nook Tablet and NOT the HD and HD+. Go to this page - http://www.barnesandnoble.com/u/NOOK-Support/379003184
Look at the images. Which device do you have?
If you have Nook Tablet or Color - then simply plug it into your PC AFTER started ADE. ADE will recognize the device and ask you if you want to ACTIVATE it. Say Yes and then you can move books over.
If you have HD or HD+ - then go to (on your Nook) Settings > Account SEttings > ADE and enter your ADE information so that you are registered. AFter that you can just move books you have downloaded via ADE to your Nook.
Someone will have to give you the directory where books are downloaded. It will be something like C: /Program Files/Adobe Digital Editions/books/
You can just move them over and it will work.