You won't get anybody typing the description of how to do that in this little box here. If you really want to learn about a particular topic (as opposed to asking a specific question about it), then the best way to do that is to search the internet for a tutorial about it. In your case the keywords would be "eclipse debugging tutorial". When I did that the first link was
this one. There were several others.
I would suggest you read this:
HowToAskQuestionsOnJavaRanch.