Difficulty: Moderately challenging
Things You’ll Need:
Step1
Purchase the upgrade software you need. Make sure your computer fits the system requirements for the system software version you're installing. Older Macs can't install the newest systems. (However, older - but perhaps not as old as your own - systems are available for free download on the Apple Web site.)
Step2
Back up your hard disk before you install the software.
Step3
Start up the computer from the upgrade CD. Put the CD in the CD-ROM drive and start the computer while holding down the C key on your keyboard.
Step4
Double-click on the CD icon.
Step5
Double-click on the installer.
Step6
Follow the on-screen instructions to complete the installation. One decision to make is whether to use the Easy or Custom installation. The Easy Install option makes sure you have all the files you need, so it's the safest. Use the Custom installation if you are certain you won't need a particular feature. (You can install or reinstall specific software components later using the Custom installation option, too.)
Step7
Reboot the computer when prompted.
Step8
Make sure all functions work, especially printer and Internet connections.