I suggest that you use eclipse.

http://www.eclipse.org/

Then, get the Ruby for Eclipse add ons: 
http://www-128.ibm.com/developerworks/opensource/library/os-rubyeclipse/

Then, run eclipse.  In the menu go to 
window->preferences->ruby->installed interpreters.  Click add and point 
to the ruby directory.

Then, write a simple program. You might copy and paste this one to start 
with:

10.times {puts 'Lloyd is the greatest!'}

and hit the run button.  It is ever so much better than "Hello world."

-- 
Posted via http://www.ruby-forum.com/.