• Back up your information to an external medium such as an external hard drive or a flash drive.
Insert the first install CD or DVD of the operating system software.
Restart your MacBook or MacBook Pro. Immediately hold down the "C" key as the computer reboots. This will cause your MacBook to boot from the CD or DVD you inserted.
See the "Welcome" dialog that asks you to pick a language.
Choose where to install the OS.
Choose your install. You'll be presented with three options: "Upgrade," "Archive and Install," and "Erase and Install."
Choose "Update" to simply update the current OS install on your MacBook. All your data, files and programs will remain intact.
Choose "Archive and Install" if you need to back up all the data on your system and import it into a fresh install of the software.
Pick "Erase and Install" if you want to erase everything on your hard drive and install a fresh version of the OS.
Choose the right setting. If you choose "Archive and Install," be sure to check the box to preserve your user and network settings. This will ensure your previous profile data is installed in the new software installation. Once you've chosen an option, select it. Click "OK."
. The Apple OS install will take care of everything from this point. You may be prompted along the way with a few questions, but the install should be mostly automatic. When the install is complete, your MacBook will restart.
Restore your data. If you chose "Upgrade" or "Archive and Install," the software will prompt you to migrate your old data to the new system. Follow the instructions to ensure your old settings and programs are transferred to the fresh install of the software.