The class assumes you know the basics of Twisted. If you've never used Twisted the class may therefore be somewhat difficult, but the exercises you will be doing should help you via learning-by-doing. At the very least make sure you read the basic Twisted documentation, or the Krondo Twisted tutorial.
The class also assumes you know Python decently, e.g. understand lambdas.
Make sure you have Python 2.7, a recent version of Twisted (12.0 or later) and zope.interface installed (Twisted depends on the latter).
Once you've installed Twisted, you can verify it's working by running the trial command-line tool; on Unix systems you can do:
$ trial --version
On Windows, in a cmd.exe terminal:
$ c:\python27\scripts\trial.py --version
$ c:\python27\python.exe c:\python27\scripts\trial.py --version
Or perhaps some other paths if you installed Python elsewhere.