Unable to run ruby in eclise helios

I want to Debug/Run ruby and Watir scripts in eclipse helios.I have
installed ruby 1.8.6, ruby-debug-ide-0.4.16.gem, rake gem.After this I
have configured “Installed Interpreters”,“ruby-debugger” to C:\Ruby .

Still I am unabe to either debug(or)run ruby scripts. Getting a message
“The selection can not be launched , and there are no recent launches.”

Need help.