adding PID to a self balancing robot

i build a self balancing Robot on soildworks then i i opened it in simscape in order to simulate it's self balance and add the PID in order to work but when i loaded the project in simscape it was hard for me to understand where to connect the PID system to the project i want to know how to connect or even where to start and understand how to connect it

[Bora Eryilmaz]

This previous question might help: how to tune PID controller for a vehicle model in Simscape?