Beginner's question: How to add PIR motion sensior to Things?

Just starting using the webthings and I love it!!! I have connected a relay on the pi gateway and added to the Things through the GPIO addon. I have also connected the PIR motion sensor through the GPIO on the pi gateway. I couldn’t figure out which addon to use to add the motion sensor to the things. Will anyone give me a hand? Thanks a lot!

Perhaps it could be added to the generic sensors adapter?

You should also be able to add it as another GPIO device, it just won’t show up as a proper motion sensor.

I gave it a try but there’s no option tell to which GPIO# the sensor is hook up. I will check out its documents. Thank you.