To turn the device on or off, click the button on the device five times in quick succession.
Install your oil cartridge by screwing it into the device.
To change the voltage level, click the button on the device three times in quick succession. This will cycle through the available voltage levels of 3.0V, 3.7V, and 4.2V.
Once you've chosen your desired voltage, press and hold the button to heat up the device and take your hit.