Setting up environment variables on windows

I create custom software.  Sometimes I need software to run on demand at random times.   In the past I would need to navigate to the directory that contains that application and run the executable, or worse, run from within the Visual Studio IDE.

I’ve since learned about the .NET Core CLI (Command Line Interface) which allows programs to be run from the command-line; this works well for .net core apps, but I have a few legacy apps that use the full .net framework – how can I run them from anywhere on my computer without having to remember where they’re saved?  By registering the path to the executable directory as an environment variable!  Steps are shown in the above screencast.