As Adam remarked, this subject has been covered before. However, a quick tip if you do not feel like internalizing the commands of the debugger, use Devel::ptkdb. It's great because it's graphical with buttons and so you do not need to remember-and-type but can instead see-and-act. (This is BTW the fundamental reason why most people are more comfortable with GUIs than CLUIs, it offloads the long-term memory and recall).

/jeorgen