Step 1: Don't cross-post. This is the appropriate forum for your request, not the dev thread.
Before you do anything, get ADB working. The instructions are in
Leapinlar's tips thread. You only need it to move the CM10 zip to the correct partition on the SD card, but there's practically no other way to accomplish that step in Windows. You'll want the CM10 zip in the same folder as your adb.exe.
Unzip the .gz (it's a compressed format like .zip or .rar, if nothing on your PC recognizes it then grab 7zip).
Install win32diskimager on your PC.
With the SD plugged into your computer, start the program and use it to write the image to the SD card (I'm fuzzy on the specifics of this process because I use WinImage, but I think it's quite straightforward and you can Google up dozens of step-by-steps).
Put the SD back in your powered-off HD+ and power it on. Plug it into your PC w/ the USB cord.
From there, verygreen's instructions should be straightforward enough. Do what he says in ClockworkMod on your Nook and use the command he provides in ADB on your PC.