The Shimano STEPS display is located by the left handle bar grip and it is used to activate the Herrmans front and rear lights which come included on Shimano powered Xtracycles.
The button to turn the lights on and off to located on the bottom of the display and can be easily reached with your thumb. Simply press the button to turn the lights on and off.
Please note that the light power is linked with the main power. The light cannot be turned ON when the main power is OFF.