Run RetinaFace pre-trained models

I have the .params and .json files (parameters and model), now what?
I would like to use this model. I am looking at the test.py sript but I have no idea how to use it with the downloaded files. Should I pass them as an argument somewhere? Should I save them somewhere speifically?

Could you write a few lines of explanation to help beginners to make this run?

Thank you in advance.