Upgrading to a new Operating System can be a pain. Apple continues to make the process easier and easier, especially from Mavericks to Yosemite. For the most part, you go to the App Store, choose to install the new Operating System and then click on the buttons that are highlighted until the process to upgrade to OS X Yosemite is complete.
The person who uses a computer will still have to click on some buttons to upgrade to OS X Yosemite. However, if you add the Install OS X Yosemite app to your apps in Bushel, all of your Mac devices will get the Install OS X Yosemite app. This can take awhile to download (after all, it is a 5.7+GB operating system upgrade), especially if you’re deploying to a bunch of devices on the same network at the same time. Once downloaded, Install OS X Yosemite should open. When the app opens, the person using the computer simply completes the process by clicking on the default options until the computer reboots. And there, one of the least painful OS upgrades you’ll ever do!