
To use it, simply connect the drive to the target Mac with the power off. It should say "Copy Complete" when it's done.
The process of readying the disk as a bootable drive will begin. You will be prompted to enter your system password the password you use to update apps on your Mac, or to login at boot. Paste that text into the Terminal application and hit the Return key. Copy the following text: sudo /Applications/Install\ OS\ X\ Yosemite.app/Contents/Resources/createinstallmedia -volume /Volumes/Installer -applicationpath /Applications/Install\ OS\ X\ Yosemite.app -nointeraction It is important to remember what your hard drive was called? If you didn't call it "Installer," you'll need to change the pathname where it says /Volumes/Installer to the name of your drive.
Open the Utilities folder if it's closed.
You may need a friend to down load Yosemite, if your purchased option is grey. I use three ways to create a boot-able OS X install drive, using the installer’s built-in createinstallmediatool, using Disk Utility, or performing the Disk Utility procedure using Terminal.