Need some help with controlers

You need to be clear on how things are setup by default and what can
be changed.

If you are using the standard routes then there is a directory app/
controllers where your controller files *.rb live.
There will also be a directory app/views/<controllername> for the
*.rhtml and *.rjs and *.rxml files that go with that controller.
For normal operations there will be one of the above files for each
action on each controller.

The URL you indicated /admin/news would indicate admin as the
controller and news as the action. If news is really a controller
the URL would normally be /news or /news/<action> with index being the
default action.

I would recommend the book Agile Web Development with Rails as it has
a very fast intro tutorial in the first few chapters to get you
oriented, then goes into everything in more detail. The book is well
written and easy to read.