How to update safari?

On your version of macOS, 10.14, you can update to Catalina by going into Menu > About This Mac > Software Update

Here is a support article with more information: https://www.apple.com/in/macos/how-to-upgrade/

Please be sure to make a full backup of your current hard drive. (Either with Time Machine, or a different service of your choosing.)

What version of OS are you running? Safari comes packaged natively along with macOS, so the best way to get the most current benefits of Safari is to update to the latest version of 10.15 Catalina.