You can do this from your WordPress dashboard. When you first log in:
https://www.your-site.com/wp-admin
On the main dashboard screen, there is a small meta box title “At a Glance” and there’s usually an update button there that should say “Update to 4.2.2”.
You can also update by your sidebar on the dashboard, and clicking on Updates beneath the “Dashboard” section. There will be a message on that page that says in bold text, “An updated version of WordPress is available.” with an “Update Now” button.
Depending on your hosting/server, there may be permissions that might stop you from updating WordPress on your own. If that’s the case, you’ll likely have to call your hosting provider.
Check this out for more info. Hope this helps!
https://codex.www.ads-software.com/Updating_WordPress
Also I want to advise since you’re updating from a very outdated version of WordPress, you take some precautions like backing up the site and database first. Check this out before you hit that update button!
How to update WordPress without all hell breaking loose…
I would definitely advise you to do some research before you try and upgrade from so many versions behind.