Before using any of uGUI renderers you must intialize your scene properly. Don’t worry if you forget to do so. When you try to create any uGUI renderer, Energy Bar Toolkit will tell you that scene must be initialized first, so nothing wrong will happend.

In order to initialize a scene please add a Canvas to your scene using Game Object → UI → Canvas menu option.

When your cavas is on the scene, you can add any uGUI bar anytime!

To know more about canvases and uGUI, please see the tutorials