Write an article based on this "Attach your external hard drive. Restart your Mac. Press and hold ⌘ Command+R. Wait for the Apple logo to appear. Release ⌘ Command and R. Click Disk Utility. Click Continue. Select your external hard drive. Click Edit. Click Restore…. Click the "Restore from" drop-down box. Select your Mac's hard drive. Click Restore. Click Done when prompted."
Plug your hard drive into one of your Mac's USB ports. You'll need the same amount of space on the external drive as is being used on the hard drive.  If your hard drive uses a USB 3.0 connection and your Mac doesn't have USB 3.0 ports, you'll need to buy and use a USB-C to USB 3.0 adapter. If you haven't yet formatted your hard drive to erase it and set it up for a MacOS backup, format it before continuing. Click the Apple menu {"smallUrl":"https:\/\/www.wikihow.com\/images\/f\/ff\/Macapple1.png","bigUrl":"\/images\/thumb\/f\/ff\/Macapple1.png\/29px-Macapple1.png","smallWidth":460,"smallHeight":476,"bigWidth":"29","bigHeight":"30","licensing":"<div class=\"mw-parser-output\"><p>I edited this screenshot of a Mac icon.\n<\/p><p>License: <a rel=\"nofollow\" class=\"external text\" href=\"http:\/\/en.wikipedia.org\/wiki\/Fair_use\">Fair Use<\/a><br>\n<\/p><\/div>"}, click Restart..., and click Restart Now when prompted. Do this immediately after your Mac begins to restart. You may also see a spinning Earth here. As soon as you see the spinning globe or Earth icon, release the keys. You should now be at the recovery screen. It's a grey hard drive icon in the window. This is in the bottom-right corner of the screen. Click the external hard drive's name in the top-left side of the page. This menu item is at the top of the Mac's screen. A drop-down menu will appear. It's at the top of the drop-down menu. You'll find this in the middle of the window. It's in the drop-down menu. This blue button is in the bottom-right corner of the window. Clicking it prompts your hard drive to begin backing up to the external hard drive.  This process may take several hours. If you get a "Restoration Failed" error, turn off FileVault and try again. This signifies that your backup is complete.