if you are using Windows 7 (or Windows 8), the last version of iTunes that will work with that is 12.10.11.2. If this applies to you, then iTunes cannot be updated to the latest version
if you are using Windows 10 (or Windows 11), - and you downloaded iTunes from the Microsoft Store, then iTunes will check for updates each time it starts up and update automatically if there is an update available. You need to take no action. There will not be an option in the Help menu to check for updates and I believe that you may not be able to confirm which version is running
if you are using Windows 10 (or Windows 11), - and you downloaded iTunes directly from Apple, then iTunes' top bar menu option includes Help/Check for Updates. Using this option will tell you if there is an update available and offer you the option to download and install it. There will also be an option on the menu to Help/About iTunes which will tell you which version you currently have