I found this site with an excellent, step-by-step method on using Winimage to create the Autonook MicroSD card. I had no clue either, but using this, plus the files from XDA-Dev, I was able to root in about 15 minutes (or less).
http://reviewhorizon.com/2010/12/how...w-and-gallery/
P.S. DON'T use the file linked to in the article! Instead, get the easier, new and improved version at:
http://forum.xda-developers.com/showthread.php?t=872490
P.P.S. I see the blog with step-by-step instructions has been updated to reflect using the Auto-Nook file (much easier!). The link is at the top of the page referenced above, or go straight there from here:
http://reviewhorizon.com/2010/12/how...g-auto-nooter/