The Kindle has a USB port for charging and you can charge with the included ac to usb adaptor, from a usb equipped computer, or from a solar or car charger that has a USB output. Our favorite is Solar.
If connected to your computer, the Kindle becomes an external "hard drive", and you can copy files to and from it with ease. We will cover file format conversion and utilities (like Calibre) in a separate post, but this is the method for getting non-Amazon content (eBooks from other sources, PDF's, MP3's, etc.) on to your Kindle.