how do I update itunes on my PC with the latest version of itunes?

It depends upon where you obtained your version of iTunes.

• If it came from Apple, click on Help/Check for Updates. If there is an update available, a message will tell you and you simply need to follow the prompts
• If it came from the Microsoft App Store, you do not need to concern yourself with updating since it's all automatic. As far as I know, there is no option on the Help menu for checking for updates