This macro works hand in hand with three skins to build the navigation depending on the user's status:

<% site.navigation for="users" %>
DEPRECATED. Since version 1.1pre2 the navigation bar for users is not supported by the site.navigation macro anymore. Navigation items for all users should be directly included in the site's main.skin. This macro call won't be supported in the final release so it's a good idea to update the user navigation now.

<% site.navigation for="contributors" %>
will be replaced with the navigation-bar for contributors (which in most cases will contain links for creating a new story etc.). if the user doesn't belong to the contributors of a weblog nothing will be displayed. If you enabled "Allow contributions" in your weblog-preferences this navigation-skin will be displayed for all logged in users.

<% site.navigation for="admins" %>
same as above, but antville will check if the user belongs to the administrators of a weblog and either render the navigation bar for admins or nothing.

To change the skins simply go to the skin editor of your weblog and scroll down to the section "navigation skins". In antville's default skinset you can find this macro in the skin "main page".