And here’s the FAQ on using custom code which will explain the terms and what a DT is and all that if you want to go into it.
But basically it’s pretty simple. You’re just going to copy the code for the virtual sensor from the instructions in the FAQ and then you’re going to paste that into your own account. Then you will use your own account to create a new virtual device which will use that device type handler.
It sounds harder than it is. You just need to follow the instructions.
Once you’ve done that, two new devices will appear in the device list in your mobile app. One will be a sensor and one will be a switch. They will show up in the device choices in the app just like any other switch or sensor. 
(My apologies if I went too fast: most people who are already using webcore are familiar with these concepts.)