You can email yourself the document to your kindle address. Go into your amazon account and go to manage your kindle to see the kindle address to send it to. I believe it costs a little bit, shows 15cents on my account.
You can possibly see if there is a way to load it from your computer. Just search it on amazon's kindle area
once you have the ninja notes saved on your computer, you can copy them to your kindle. all you need to do is plug the kindle into the computer and open the kindle file and copy and paste the ninja notes…that has worked for me.