upgrade your Mac to macOS Sierra

Now upgrade your Mac to macOS Sierra from the Mac App Store -Free

Link: https://itunes.apple.com/us/app/macos-sierra/id1127487414?mt=12&ls=1

Mac models are compatible with macOS Sierra:
MacBook (Late 2009 or newer)MacBook Pro (Mid 2010 or newer)MacBook Air (Late 2010 or newer)Mac mini (Mid 2010 or newer)iMac (Late 2009 or newer)Mac Pro (Mid 2010 or newer)

General Requirements

• OS X 10.7.5 or later
• 2GB of memory
• 8.8GB of available storage

For details about your Mac model, click the Apple icon at the top left of your screen, choose About This Mac, then choose More Info. 

• If your Mac is running OS X Lion 10.7.5 or later, you can upgrade directly to macOS Sierra.
• If you’re running Snow Leopard (10.6.8) and your Mac supports macOS Sierra, you will need to upgrade to El Capitan first.

Before you upgrade, we recommend that you back up your Mac. You should also have your Apple ID and password handy. 

How to upgrade 

Visit the macOS Sierra page on the Mac App Store. Click the download button.Enter you Apple ID and Password.File Size of 4.77GB will get download in your Application folder.Double click the file and follow the onscreen instructions to begin your upgrade.