right click in your content browser and do UserInterface > Widget Blueprint. By default its scaled to full screen, i usually scale it down to about 500 x 500 (this may be different depending on what your using it for). To give you the visual effect your looking for, turn down the opacity of the widget components. Then you add the widget as a component to whatever blueprint has your camera. Note: widgets are still experimental in unreal and may not always give the results your looking for.