Upgrade to OS X Mavericks. Free on the Mac App Store.

For the first time, you can upgrade your Mac to the latest release of OS X for free. Just click the Mac App Store icon on your Mac. Download OS X Mavericks. And your Mac does the rest. Follow these steps to begin your upgrade.

How to upgrade to OS X Mavericks

Download OS X Mavericks

Open the Mac App Store and click OS X Mavericks. Click the Download button. Then follow the onscreen instructions to install it.