On WIndows, you'll simply click the Red X on the upper right of your window, or click File from the Menu Bar and then close.
On Mac, those buttons are reversed as they reside on the upper left corner of the window.
Clicking the Red button on your app's window does not end the app.
You can do so by using different two methods: A) Go to the Menu Bar, click the App Name you are currently in, then scroll down to Quit <app name>. B) Right click the App you want to end on the Dock, then click Quit.
You will know an App is open when you see a small dot under the App icon on the Dock.