Connect to mdb42q from pi and control it ?

maybe I didn't explain correct
I have connected to the mdb42q a LED in GPIO D15 (it this OK?)
I want to control the LED from the PI
I have the MAC address of the PI - I want it to connect only to it
DC::32::9A:**

I have found this - and I can see it connect to the pi

var gatt;
NRF.connect(" DC:**:32:**:9A:**").then(function(g) {
  gatt = g;
}).then(function(service) {
  console.log("connected");
  return gatt.startBonding();
}).then(function() {
  gatt.disconnect();
 console.log("Done!");
});

what else do I need to write in order to make hi m"wait" for my command ON\Off?

and do you have an exapmle what need to do on the pi side?