Model not found???

you model class is fine the way it is.

in app/controllers/UserController.rb you should have a method that has
the same name as the template you want rails to automagically call. This
method needs to pass the template a class variable (preceded by a '@')
the template can have access to:

def list_users # same name as template
  @all_users = User.find(:all) # note @ before var name
end # no need to invoke anything

then in app/views/users/list_users.rhtml you can access the collection
of users via the class variable @all_users

example:

<ul>
  <% foreach user in @all_users %>
  <li><%= user.name </li>
  <% end %>
</ul>