Debug python - Error: No main class specified?

[elenaflorence]

I installed Intellij 2019 with python plugin. And I opened a directory with python scripts. I'm going to debug script1.py in the directory.

In the "Project Structure" window, I added new Python in the field "Project SDK".

Then, I went to "Run/Debug configurations" folder and clicked the + and added a new Application, I need an command line argument so I filled the field "Program arguments:" with my arguments.

However, at the bottom it shows a read error message: "Error: No main class specified". And I cannot run the python script. What I missed to set up the intellij to run python script?