Download and install are fully documented on Tulip's website. From now on, I'll assume you are using Tulip on Windows (and have installed the latest release (using the autoexec install bundle).
Tulip will also be available from computers accessible in your classroom. From now on, it is assumed you have access to Tulip and that you are able to launch it and use it.
This is a rather common way of looking at things shared by the InfoVis community. The good thing about it is that everybody agrees on it. Another good side of it is that the pipeline tends to conciliate both the user's perspective and the engineering perspective -how you build a viz system). The bad side of it is it focused on the automated side of InfoVis (processes and algorithmic) rather than on cognitive processes.
Here are a few picks collected on the net:
Dealing with graph hierarchies is certainly one of the most powerful feature of Tulip. Invoking plugins to build hierarchies and compute quotient graphs almost turns visual analytics into a video game (!). Here is a file containing a script building a two level hierarchies and associated quotient graphs (at both levels).