So here is a rather lengthy video on the subject of making use of UMG found in the Unreal Engine to make a healthbar. The video is not meant for absolute beginners though and involves the use of Paint.NET to make a simple asset that we need, as well as making use of Blueprint nodes to make an interactive HUD.
The real goal here is to teach you how GUI is built efficiently and robust using UMG in the Unreal Engine.