There are some pretty good tutorials online. Onlamp's is a pretty good one of many.  The problem with many is the lack of an explanation of dev, test, and production environment set up.  These tutorials suggest utilizing the following URL http://127.0.0.1:3000/  The issue is ensuring there is a Rails testing compiler, (ex: Mongrel) installed. The key is running development locally and then deploying to a production server, publicly.  

One of the best tools for developing RoR applications, Instant Rails.  This will allow for local development. It comes with Apache MYSQL and full RoR support - which includes an easy interface to run the development environment, Mongrel.

For more advanced help there are some pretty good books on the market.  Sitepoint's Simply Rails 2 is a great resource that also comes with example scripts.  It can be downloaded as a PDF.