To turn the app into full screen mode on your Mac mini you have to use a mouse or trackpad. Move the pointer to the green button in the top-left corner of the app window and click on it. The app window should transform into a full screen. Alternatively, you can move the pointer to the green button and choose “Enter Full Screen” from the menu that appears.
In full screen mode, you won’t see any menu bar or frames of the window. To show or hide the menu bar: Move the pointer to or away from the top of the screen. To quit full screen mode simply click on the green button in the same place as before.