how to update my Mac book pro 2011 to latest version of safari

This is hard to answer without our knowing the macOS version is the computer you are now running.

Safari versions are inexorably tied to your computer's macOS version. Your 2011 Mac can run up to macOS 10.13 High Sierra. That gives you Safari 13.

If you need to upgrade to 10.13, a link to the upgrade is included in this AppleSupport article:

How to get old versions of macOS - Apple Support

You can't; the current Safari version requires at least Mojave. If desired, use a product such as Firefox.

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