This will guide you through updating the Mac Operating System, or just the software on your Mac.
2. macOS: Software Updates
Click on the Apple Menu and click on App Store.
Click Updates on the top-right.
Click Update All to perform your software updates.
3. macOS: OS X High Sierra Compatibility Check
In general, if your Mac was made after late 2009, it should be compatible. We can confirm using the following steps:
Choose Apple menu > About This Mac.
Check the OS version.
Compare what it says here to the table below to make sure your Mac is compatible with macOS High Sierra: Mac ModelOS Version
iMac models from late 2009 or later
MacBook models from late 2009 or later
MacBook Pro models from mid 2010 or later
MacBook Air models from late 2010 or later
Mac mini models from mid 2010 or later
Mac Pro models from mid 2010 or later
macOS Sierra
OS X El Capitan
OS X Yosemite
OS X Mavericks
OS X Mountain Lion
4. macOS: Check Drive Space
Click the Apple menu, then click on App Store.
Click the Storage tab.
Free space is the first number you see below the name of your hard drive.
Disk space needs will vary depending on how you use your computer. In general, if you have over 15 GB of free space, you should be fine for updates and upgrades. Only proceed if you have less than 15 GB of free space.
Click Manage... to the right of your hard drive.
Under Recommendations on the left, you'll see some very easy-to-use tools to help optimize and clean up your disk space, such as optimizing the files already stored in iCloud, removing items from iTunes you've already watched or listened to, emptying the Trash automatically, and reviewing the files stored on your Mac to delete unused or old ones.
5. macOS: Backup Check
It is important that, from here on out, you have a recent backup copy of your computer's contents. While none of these steps should cause problems, they can. Having a backup in place provides peace of mind, should anything go wrong.
6. macOS: Upgrade to High Sierra
Choose Apple menu > App Store....
Search the App Store for macOS High Sierra in the top-right corner.
Choose macOS High Sierra from the search list.
Click the Download button on the High Sierra page. A file named Install macOS High Sierra downloads to your Applications folder.
After download is complete, the installer opens automatically. Click Continue and follow the onscreen instructions.
You may be asked to sign in with an administrator name and password to install a helper tool, then click Add Helper to continue. This is usually the username and password you use to sign on to your Mac, or the one you created when you first setup your Mac.
7. macOS: Backup
Purchase an external hard drive at least as large as how much information you have to back up. To see approximately how much space you'll need:
Choose Apple menu > About This Mac.
Click the Storage tab.
Connect the external hard drive to your computer, and power the drive, if required.
Choose Apple menu > System Preferences.
Click Time Machine.
Click Select Backup Disk, Select Disk, or Add or Remove Backup Disk.
Select a backup disk from the list, then click Use Disk.
Click the Time Machine
icon on the top-right side of your Mac, and choose Back Up Now.
Your initial backup will take a while to complete. Do not turn off your Mac, but you may continue using your Mac. A message will pop-up in the top-right corner letting you know when the backup is complete.
You can check the status of the backup by clicking on the Time Machine
icon in the top-right.
8. Mac: Upgrade
Your Mac is not compatible with macOS High Sierra.
You may choose to continue using what you have, or contact Apple about upgrading to a new Mac.