Re: reverse/forward backwards?? prop spins wrong way!?
I don't understand how you rewire to change the reverse/forward direction? There are no electronics involved in the forward/reverse mechanism. Normally on the throttle housing (the big lever that you push forward or backwards to make the boat move) there are two ways of connecting the shift cable so that forward is forward and not reverse. If your engine is starting backwards (Highly unlikely), then you have the wrong starter motor, but again you don't rewire anything. You have a mechanical problem, not an electrical problem (well you do have an electrical problem now! but going the wrong way was not an electrical problem!).
If your problem is a simple as the throttle lever working in the wrong direction, then you need to find what make and model of throttle you have and get the manual, it will tell you how to reverse the shift direction. You should not need to rewire anything, as it sounds like the boat worked before, just went in the wrong direction, I would suggest putting all the wiring back to how it was and then get the manual for the throttle lever mechanism.
As Don, says, tell us the make, year and model of boat/engine/outboard and you might get some better answers. My crystal ball died years ago!! Good luck fixing it.
Gary