CI Build on fork update

Hey guys!
I’m having some trouble setting up a automatic build for our own ghidra.
At the moment I have to repo’s

  1. ghidra-ci
  2. ghidra fork
    ghidra-ci should build our/my ghidra fork when the fork is updated (pushed to it or pr merged)
    But currently ghidra-ci only builds when the ghidra-ci repo is updated.
    So, it builds when I’m updating the wrong repository. I have read about some token, but I don’t know how I should accomplish that