Howdy Shradhdha!

That's the same article I used to get started too, waaay back in Oct
of 2005! Well, let's look for some clues.

If you type "ruby -v" at a command prompt, do you get version
information for Ruby? If so, then Ruby is probably installed correctly.

If you type "gem list --local" at a command prompt, do you get a list
of the gems you have installed locally? If so, then RubyGems is
probably installed correctly.

If you read through your list of local gems and find "rails (x.x.x)"
(or whatever your version is), then the rails gem is probably
installed correctly. Of course, you should probably also have the
following gems: actionmailer, actionpack, actionwebservice,
activerecord, and activesupport.

This should at least give you an idea of where in the installation
process you need to revisit. Hope this helps!

-Colman