import a user created python file as module

[Phoe6]

Hi,
     I have the following directory structure in my project.
Base:
         file1.py
         file2.py
         Directory1:
                       file1-dir1.py

I am able to import file1 into file2.py
What I need to do is, import file1 in the file file1-dir1.py.
I did not create the entire dir structure as package. Adding
__init__.py file in both Base: as well as Directory1: is not helpful. I
am unable to import file1 in the file1-dir1.py. It is not able to find
the path of the file1.py.

How and what should I do to import file1.py into file1-dir1.py ? Please
give me some references to the tutorial topic which I can study as
well.

Thanks,
Senthil