route.rb parameters

I set up VirtualHost in Apache which works fine to the "public" directory, however attempting to connect to the app/controller is problematic.

i.e. The page returns this:

Routing Error no route found to match "/music_library/admin" with {:method=>:get}

My guess is that I need <something>/:controller/:action/:id

I don't completely understand mod_rewrite, but is there some comprehensive documentation which explains what the default rewrite placeholders are for route.rb.

Seems like I need :url/:controller/:action/:id or :application/:controller/:action/:id

or something.

How the heck do I find out which one is the appropriate option other than hours of futile guesswork?