1. Under the Devices tab in your Harmony app tap Edit Devices, then + Device
2. Select ZIGBEE/Z-WAVE DEVICES and put your On/Off Plug-In Switch in pairing mode by pressing the button on the front quickly 3 times
3. Once the Plug is found you can tap the pencil icon to rename it, then tap the X in the corner to go back
4. Tap Done on the bottom and your On/Off Plug-In Switch is ready to rock
Your On/Off Plug-In Switch will be listed under Plugs and can be toggled by tapping on the icon next to its name.
If you want Harmony to automatically turn on a lamp when motion is detected, check out this article: