I am new to sdk, adb, sideload, etc. I tried twice to update from 4.4 to 4.4.2 with no joy. I am on a MacBook Pro, so ran into a few issues before finally succeeding (!) on my third try.
1. On a Mac, commands are given in Terminal. Applications > Utilities > Terminal.
2. In Terminal "cd" is the prefix command to select location.
3. In Terminal "./" must immediately precede "adb" .
4. Safari automatically unzips "safe" files. I was trying to use an unzipped folder. Disable auto-unzipping in Safari thus: Safari > Preferences > General > Open "safe" files after downloading: uncheck.
I know all this information is out there, and there is probably a great tutorial that I missed. I think all my trial and error was a good thing. I got to feel my way through some of the processes and not just follow a set of instructions. Thanks to the Android community for the encouragement. I'm glad I kept at it, it feels great to have the update through my own efforts, rather than waiting and checking my phone for the updates to be pushed to me.