Excell 2003

If lastreading limit And NLastreading limit Then
AlrtMsg = (LineId & " Water Excursion(2) " & Hr2 & ":55 over by " &
lastreading - limit & " gal.")
Call WaterAlrt(LineId, AlrtMsg)
End If

How can I determine where WaterAlrt is located? Part of this macro is
sending a call to it but I need to locate exactly where it is at to edit it.