Add commandline app shortcut How do I run the app: ~/ngrok by typing ngrok?

I want to add a shortcut to the ~/ngrok location so that I don't need to know the place where it is when I run the app.
Commands in *nix terminals are stored in various directories throughout the filesystem. The PATH variable is a series of colon (:) sperated directories that are searched in order to find a desire command. When a command is called, the PATH variable is read, and all the paths is contains are checked for the command in question.
You have 2 ways to make your program run without specifying location: either add it to a directory that's already to your PATH variable, or add its containing folder to the PATH variable.
You can read your current PATH variable by running:
echo $PATH
And you can edit your PATH variable by following a guide such as this one
P.S. I REALLY strongly discourage keeping files directly within ~/