Debugging.

I am now to the point of attempting to tackle debugging in WDSC. All of
the instructions I read were very confusing. I called IBM to get some
help there - and was led to Help/Cheat Sheets. Unfortunately, the cheat
sheet titled, "Debugging a 5250 RPG or Cobol application" was out of
date, and the instructions didn't match WDSC menus, etc.

I called back, and we started playing with WDSC, not making much headway
when the IBM'r said that he preferred using the Graphical Debug
interface. He led me through iSeries Navigator to this completely
different debugging method.

I would like to use whatever is the "best" debugger available to me. 

What do you use, and why do you consider it better than the alternative.
And, what's the best way to learn it?

Thank you,

Dave