How to download macOS
Apple launched the next version of its operating system for Macs in WWDC 2016 but this time, it is called as MacOS. Even though you can get the final version of MacOS Sierra by only waiting for few months, if you are not a patient person, you can get the beta version of macOS right now.
What is worth mentioning is that you should not download the beta version on your main computer because there will be bugs and these bugs may affect your computer’s performance and battery life. Also, you should always take a backup of your documents.
Anyway, first of all, if you are not a developer, you cannot get the macOS right now, but in July. All you need to do is to sign up to Apple’s Beta Software Program and then you will see the steps to install the macOS to your computer.
However, if you are a developer ( which means you are paying $99 to Apple each year to be entitled as a developer ), you do not have to wait. Just go to Apple Developer Download Center and again follow the instructions.