Select Install macOS (or Install OS X) from the Utilities window, then click Continue and follow the onscreen instructions. Learn more For more information about the createinstallmedia command and the arguments that you can use with it, make sure that the macOS installer is in your Applications folder, then enter this path in Terminal. If you're using a compatible disc and you don't see it from Remote Disc, make sure the sharing computer is turned on, is connected to the same network as your Mac, and has a compatible CD or DVD in its optical drive.
Image via Before You Start The obvious first step here is to. But before you do anything else, a word of caution: once you've used the OS X installer, it will automatically delete the file you need to make the backup disk, so you'll want to either make a copy of the installer or create your disk before you upgrade. You can use a USB flash drive, external hard drive, or DVD-R disc, but the USB drive is quicker. If you're using a USB drive, it has to be formatted as 'Mac OS Extended (Journaled)' and set to partition type 'GUID Partition Table' in order to work. Image via Once inside, browse to the ' Contents > SharedSupport' folder where there will be a file called ' InstallESD.dmg.' This is the image file that contains the information you need to create the backup disk.
Step 2: Open Disk Utility (located in your Applications > Utilities folder). Step 3: Drag and drop the ' InstallESD.dmg' into the list of drives on the left and select it. This should make it appear in the Source box on the right. If not, you may have to click the ' Restore' tab as seen below.