debugging Jquery

debugging Jquery

Hey guys i have been just trying to debug a few javascript plugins and i'd really like to learn the mozilla debugger tool . here is a screen shot of what i had when i was debugging my plugin : 

on the left hand side you have all the events and on the right hand side u'll see DOM2 and bubbling , can somebody give me a vague idea of what this really means ?? and how useful are these options while debugging .. ? 

Thank you .