The guide here is helpful for auto-nooter:
But I did make a mistake in "Let's get started part," in these steps:
4 Insert AutoNooter SDcard into your NOOKcolor.
5 Plug the USB cable into your computer and your NOOKcolor. (This will boot up the NOOKcolor.)
In steps 4 and 5 it is critical that your NookColor is powered-down all the way. To do this you have to press the power button for around 5-10 seconds (or longer) then a prompt will appear asking you if you want to turn it off.
Also, if you're not sure, it's better to ask first before doing anything else! Generally if you're not sure of anything, don't put the SD Card in your nook yet!