You have access to a running zena site (e.g. an account for the zenadmin.org Wiki) and want to post content? Read the User’s Guide.
Read Getting Started, or use the scripted install for debian servers.
To learn what zena is capable of, look at the features. For an easy introduction, we recommend looking at the Tutorials.
Learn, design, adapt …
In order to master zena, you should start to see and improve The Guide to Zena. You could then jump into the details of zafu, either by reading the documentation or the template sources from existing skins.