I’m new at automation…
I setup Hassio (flashed the hassos_rpi3-3.7.img to sd card) then added Node red from ADD-On Store, everything works fine but i can’t get the GPIO node ( node-red-node-pi-gpio ) to connect to Raspberry pins and get respond
I’m sure it’s easy but i’m struggling, Thanks!
When you run hassio all devices are passed into the home assistant container.
Add the gpio PIN to HA and use those ha devices in node red
Thanks it helps 
Subsidary question; how to add a GPIO PMW pin to HA in order to use this pin with the slider node in Node Red?
Forget about node red for a minute.
Get your items added to HA per the documentation so they show up as switches/senors in HA.