how to debug rubny on rails application on aptana 3 studio

Hi i am using rails 3.0.12 and ruby 1.9 and Aptana studio3, just i started to learn ruby on rails , i got one sample project from open source, i want to debug and see the flow of compiling. i am not getting how to debug rails application line by line and how i see the values while debugging, any one have idea please help me out.

Thanks in advance

V.Venkat

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