First of all is you friend's nook tablet 8GB or 16GB model?
Second you haven't read my FAQ, so you haven't read enough and you're confused in the way a custom rom and B&N stock update.zips are flashed.
A custom rom you can install from cwm > install .zip from sdcard or if it's a backup folder a.k.a recovery rom (as Albert call it) you can restore it from backup & restore option in cwm; but if it's a B&N stock update.zip you flash it "as is" in a different way, you have to format a sdcard with fat32 file system and set primary partition to "active" then you can flash the .zip from the sdcard. There is no need of cwm BUT there is need of stock original recovery as their update.zip requires their stock recovery to work.
Read my thread how-to restore internal partitions with 'dd' command for more information about flash stock/custom recovery and flash B&N stock update.zip for an out-of-the-box nook which means start from scratch: rooting, bla bla bla.
If you dont want to start from scratch then grab a custom stock rom from development section and flash it in cwm. Albert, cobrato and i have posted them.
Third this is not Q&A, wrong section to post. There is a sticky about it.
Sent from my Nook Tablet using xda premium