I keep the wi fi off until I need it. You can do it from the little gear box on the top right of the Kindle. The send file to Kindle program is here:
http://www.amazon.com/sendtokindle
The Kindle site at Amazon has all the info how to do a lot of things with the Kindle other then just books. The Discussion site is great. Lots of tech expert answering questions about Kindle. Everything from rants to raves. If you have a Kindle why not learn how to use it to it's fullest?