To trace or write, you need to secure what you are working with. The clips take care of that. They are designed to slip over the edge of the acrylic plate and exert a slight pressure. Use them to hold the template and paper in place by carefully slipping them over the plate and papers as shown above.
Shown above is a piece of stationery over a piece of vellum with guidelines printed on it. With the back lighting the lines show through nicely.
You can use the Bluefruit LE Connect app on iOS and Android to control your lightbox. There's a guide to get it up and running and talking to your lightbox. Specifically, you'll be using the color picker feather of the app. See the bottom of this page in the guide.
Set the color such that your light strip illuminates your workspace to the color and intensity you like.