DeeperGroove

I am working with a WK-3500, and having trouble understanding how to accomplish certain things. The manual says that there are a variety of files with Z00 through Z09 extensions, which hold sets of parameters. I wanted to be able to load files from the Casio Music website, but the only files available there have CTK extensions. How do I extract the files I want, and how do I load them into the keyboard ? I am looking for specific instructions on loading rhythms into the user rhythm locations, but I didn't see anything about that in the manual. Also, is it possible to edit or create rhythms on the WK-3500 itself, or does that need to be done on a computer and then exported and copied to a diskette ?