Things youll need is Small micro sd card. 1 gb will work but 2 gb or more recommended if you intend to back up your rom to this card. Each backup is about 1 gb so if you intend to save backups on your card, you'll need a minimum of 2 gb.
Adapter to plug it into your computer (usb adapter is the cheapest and works the best)

What you'll need to download:


pick the size of your sdcard


youll also need to download the ROM of your choice and the ggApps file that matches your ROM
all download links will be in the spoilers

Lets begin

Flash with Win32:
You'll need a bootable CWR sdcard. click spoiler for link with instructions

1;To maximize battery performance, make sure your battery is charged to 100% before flashing. I prefer to let it charge during the flashing process.

2;Plug your bootable sdcard into your computer and copy the files you downloaded (rom, gApps) to it. When it finishes copying, safely unmount it from your computer by clicking on the "safely remove hardware" icon by the clock in the lower right corner of your screen. This prevents causing file system problems and should always be done when removing a usb drive.

3;Remove the sdcard, plug it into your powered-down NC, press the power button and it should boot into Recovery
Make sure CWM Recovery says it's version If it's any number less than that, you need to update your card, otherwise it'll fail when formatting data, leading to all sorts of nastiness.

(To use recovery, up/down volume buttons are used to navigate up and down, press the power button to go back, and press the "n" button to do the highlighted task. Only briefly press the buttons since it's easy to skip a step by holding down a button too long.)

4;Press up or down volume button until "mounts and storage" is highlighted, press "n" button.
use up/down to highlight "format /system", press "n"
highlight "yes - format", press "n" (always watch for errors)
when that finishes, highlight "format /cache", press "n"
highlight "yes - format", press "n" when that finishes highlight "format /data", press "n". (You need to format data if coming from the stock B&N rom.)

5;press power button briefly to return to previous menu
select "install zip from sdcard", press "n"
select "choose zip from sdcard", press "n"
select your CM rom, press "n"
highlight "Yes - install... (rom filename), press "n"

6;Make sure your rom completed successfully (about 5 minutes), then flash Google Apps.
select "choose zip from sdcard", press "n"
select your gApps file, press "n"
highlight "Yes - install... (gapps file name), press "n"

7;Make sure your gApps completed successfully, then press the power button until "reboot" option is visible. Remove your sdcard, then select "reboot system now", press "n"

8;Let your nook sit for 5 minutes to settle

9;If you formatted data, you'll need to do these steps:
Connect to your wi-fi: drag status bar up from bottom (you'll see a wifi icon on it), choose wi-fi and enter settings. O/W Settings > wireless and network > wi-fi settings
Set your clock: Settings > Date & Time > Uncheck Automatic and select your time zone
Sign in from Market (Market may not show in app drawer until you are connected to wifi; if you still dont see it, reflash)
Your purchased and recently installed apps will start to download and install. I find it best to just let it do it's thing for about 10-15 minutes until it completes or errors out (a possibility). When finished, reboot and check Market again.
After installing a new rom, expect it to be sluggish for a day or so.
enjoy (biggrin)

credits to colchiro