When I got my Christmas pressie - the all singing, all dancing version of the Kindle, I plugged it into my laptop and without any fuss, three folders appeared. I then managed to download some free software that converted a number of books that I had previously downloaded in various formats into the one that the Kindle understood and I was immediately able to read them, Kindle style. Only after I had started reading did I sign up to the Amazon Kindle bookstore and although I still haven't downloaded anything from it yet I have had several hours of reading fun with the unit.
I get the impression that making subfolders from those already there is straightforward. Whether you can make enough to store approach plates in an appropriate manner, I wouldn't like to say.
P.P.