Simple Question - ' defined as "a". ?'

[Gribouillis]

Python path means my main fils should be in the same directory. right?

No, the Python module path is a list of directory that you can print like this

>>> import sys
>>> print(sys.path)

Then you can learn how to modify this list if needed.

Also don't hesitate to read the official documentation about modules, although it is perhaps too exhaustive for a first approach.