Confusing python path2

Lets clear things up:

I want to add a path to PYTHONPATH so Python doesn't complain about not finding a module(a library)/cannot import a module. 
From my terminal emulator(console, terminal)

$user: export PYTHONPATH=$PYTHONPATH:/path/to/my/module

From inside a python module

import sys

sys.path.append('path/to/my/module')

I want python to always find this or that module

$user: gedit ~/.bashrc

export PYTHONPATH=$PYTHONPATH:/path/to/my/module

Or
From the first file.py you run

import sys

sys.path.append('path/to/my/module')

This is different that then system PATH
This other path is used to find binaries/executables in your console/terminal emulator. You modify this other path using:

export PATH=$PATH:/path/to/a/binary

So you can run your shiny new binary/executable like this
$user: binary


And if you want to modify this path from inside python you do:
import os.environ['PATH'] += ':/new/path'
This only affects the current session and its practically useless unless you are doing some weird bash inside python stuff. Remember that you use : to separate paths.