Welcome to the eZ Publish community portal. About your question, you might want to also install eZ Publish *with* the Web Interface (eZ Webin), this is an option during installation.
This eZ Webin extension also provides extra classes and features, one of them being an Event calendar.
I followed the link you suggested and I have got the ezwebin_site_clean site working.
I've been able to add a diary event and other useful features.
I would like to modify the templates and stylesheets to create the look and feel I need.
Should I edit the files located under: /ezpublish/extension/ezwebin/design/ezwebin/
or should I create a new site in a way similar to that described in: https://auth.ez.no/ezpublish/documentation/building_an_ez_publish_site/creating_the_tscm_site
If I need to create a new site in a different way can you please point me to a page that explains how?
The articles are a bit old, but still relevant, and should give you an idea how to modify the look and feel. If you perform a search on this portal for the keyword "design" you will also find some relevant information such as http://share.ez.no/forums/setup-design/creating-custom-design/(language)/eng-GB. This explains it is best practice in eZ to create your own design in an extension, and not modify any default designs (templates and css).
Let us know if you need more information. Regards, Robin
Board member, eZ Publish Community Project Board - Member of the share.ez.no team - Key values: Openness and Innovation.