Layout & Launch

The dock is at the very bottom of the screen. If you move the mouse down there the icons get larger so they're easier to see. Move the mouse away and the icons get smaller so they take up less screen real estate.

You can tell if an application is launched by looking below the icon on the dock. If there is a dot below the icon, then application is launched. If you see that ProPresenter is launched but don't see it, scroll the mouse to the right side of the dock. It may be minimized. When you find it, click on it and it'll zoom back to its position on the screen.