You can send personal documents to your Kindle's email address. If you have multiple Kindles (and there are many of us out there) each one will have its own unique email address. You can change the email address (the part before @kindle.com) and add additional email addresses to your approved list of senders by going to the Manage Your Kindle area on Amazon.
You will need your Amazon.com email address and password to get into this area.
You can also get to the Manage Your Kindle area from the main Amazon screen by clicking the words Your Account at the top of any Internet screen on Amazon, then (after entering your user id and password) scroll down to the Digital Content area and click the words Manage Your Kindle.