I am new to PyCharm. I have a directory that I use for my PYTHONPATH: c:\test\my\scripts\. In this directory I have some modules I import. It works fine in my Python shell. 
How do I add this directory path to PyCharm so I can import what is in that directory?
In PyCharm Community 2019.2/2019.3 (and probably other versions), you can simply:

right-click any folder in your project
select "Mark Directory As"
select "Sources Root"

Modules within that folder will now be available for import. Any number of folders can be so marked.
PyCharm and PYTHONPATH