I want to know if one outlet is on the same circuit as another and I'd like to go to the panel and know which breaker is for which outlet.  I don't know how to ask google that question.

What tool do I need?

I think this is it   http://www.smarthome.com/90274/Extech-Instruments-CB10-AC-Circuit-Breaker-Finder-and-Receptacle-Tester/p.aspx