[galaxy-dev] How to use Galaxy API?

Hello, I want to know how to use Galaxy API(the path is /galaxy-dist/scripts/api). I follow the README but get errors. For instance, I have generated my_key and use this script: ./display.py my_key http://localhost:4096/api/libraries I get an error: <urlopen error [Errno 111] Connection refused> I do not know how it happened. Please tell me how to fix it. Thank you! In addition, my main purpose is to manage the data library in another system. Should I use the api such as library_create_library.py, library_upload_from_import_dir.py and so on?