Hi! Sorry for the delay. Finally I "buyed" some free ebooks, don't know what the problem was so i deleted my credit card and address, added them again and finally works
Thanks for the help!
One thing that I find is that you can "buy" free books from Google Books, don't understand why don't they let us to download them straigth from google books and have to buy them as they were from B&N
I bought a SD card and installed it without problems
Now my Nook has 5 Gb!
Did you rooted it? Any advices about that? (know that void my guarantee but the posibillity to take it to US for using it they are totally imposible )