Place SandPuppy Flash on your back with print inside on the affected part, strap the extender with a velcro to your comfort, connect one end of the switch to the power adaptor, plug adaptor in a socket and switch on. Long press switch to start, a red light will be seen on the switch, press once to keep in that mode. If you want lower heat, press again and you will see white light, if you need lower heat further, press again and you will see blue light. Long press to switch off.