After trying for half an hour and reading the FAQ and all the posts about enabling dual monitor service with Zionworx 2.5, I finally figured it out and decided that nowhere did I find the complete instruction for doing so. Herewith is my attempt for the benefit of other new users.
1. Your computer must have a dual output video card; most laptops do. Go to Display Properties...Settings. You should see two monitor icons (blue rectangles) labeled 1 and 2. Make sure monitor 1 is on the left and monitor 2 is on the right.
2. Click monitor 2 and check "Extend my Windows desktop onto this monitor". You should now see a blank desktop screen (without icons) on monitor 2.
3. Start Zionworx. The screen on monitor 2 will go dark. In Zionworx, get the lyrics to display on the bottom center of the screen. Press F12 (show background and text). Lyrics will show full-screen on monitor 2. Alternatively, press F11 to show background only on monitor 2, or press F10 to fade to black. There are also buttons on the right side of the button bar to do this.