Here's a list of file types recognized by Kindle:
Mobipocket files that have Digital Rights Management (DRM) protection applied are unable to read on your Kindle. If you purchased a Mobipocket file from a Mobipocket retailer, you will not be able to open the file on your Kindle.
EPUB eBooks are not supported on your Kindle.
If it is not listed above, conversion would be necessary to read the file on your Kindle. Here is a free conversion / management program - http://calibre-ebook.com/
Once have the correct format verified may transfer files via usb -