Trouble using events plugin
The events plugin by Pixel &amp; Tonic is an example of how to use custom Elements if you're building your own plugin. I don't think it should be used in a production environment (but please correct me if I'm wrong). 

If you want to use it, you should take a look at the only variable for this plugin.
This variable gives you the ability to get all events, filtered by your criteria. There's no way to get all calendars, only events:

{% for event in craft.events.events %}

{% endfor %}


One other plugin you could have a look at, is this one, still in private beta.