PY files:-

The simplest would be Notepad on a PC or TextEdit on a Mac. Whatever you use be sure that it does not save the file with any unwanted formatting such as font or paragraph tags.

Python comes with its own editor called IDLE. This is the one that I use. In my stand alone Python installation it is located at C:Python26Libidlelibidle.pyw

Poser 9 and Poser Pro 2012 both include a version of Python with IDLE in it. Try starting it by double clicking the file "idle.bat"

Other than that a Google search for script editors will bring up a substantial number of links.

Hope that helps.