The scripting engine can be used to create plugins or to enter commands and access advanced features directly in Graph. In both cases you need to install the 32 bit version of Python 3.2 from http://www.python.org. Documentation of the Python language may be found installed with Python or online.
Plugins are Python scripts and are usually distributed in source form as .py files.
The plugin files are placed in the Plugins directory where Graph is installed, and will automatically be found and loaded by Graph.
A plugin will usually register some a callback function to be called when some event occur when the plugin is loaded.
This can for example be a function that is called when a menu item is selected.
This function will when do the actual work of the plugin.
The work done when the plugin is loaded should be kept to a minimum to keep loading time low.
You can also use the scripting engine through the Python interpreter shown when you press F11 inside Graph. In this interpreter you can write Python expressions and that way do very advanced things. It is also an easy way to test code before it is used in a plugin.