You should also have your Apple ID and password handy.
Then, if your Mac is running OS X Lion 10.7.5 or later, you can upgrade directly to mac OS Sierra. Click the download button and follow the onscreen instructions to begin your upgrade.
In this article we explain how to download and install mac OS Sierra on your Mac.
For information about Apple's terms and conditions for using Sierra read: Should you agree to Apple's terms and conditions Follow these instructions to install mac OS Sierra, also known as mac OS 10.12 on your Mac.
You get access to new features that make your Mac even more useful and fun.
Upgrading ensures that you have the latest security features and performance enhancements. Before you upgrade, we recommend that you back up your Mac.
These OS versions can upgrade to Sierra: Disk space: 8 GB of free space on drive.
In the same About this Mac menu select "Storage" tab.
If you don’t have broadband access, you can upgrade your Mac at any Apple Store.