By now your soldering iron should be warmed up.
(If not, go ahead and get yourself a drink ... you've earned it, didn't you :) )

First you'll have to de-attach those two wires that are currently soldered on to the connection points. Very easy to do this: you just heat up the soldering tin on the connections and at the same time, pull the wires off.

Here comes the "hard" part - that would be not messing up the cables ... make sure you got the right order of cables. As can be seen on the pictures, I'm using a brown/red/orange 3-wire connector. Pretty easy one, since red represents +12V (which will be connected to the center connection point on the PCB), brown stands for ground connection (right connection point) and orange will be for RPM monitoring (indeed, the left connection point). If you're not sure, then look at the 3-wire connector itself. Top-side view (>> last picture of this howto, that's what I mean whit top-side) with the holes point away from you : right = ground, center = +12V, left = RPM monitoring..



Soldering with your left hand and taking a picture at the same time results in some crappy picture :)

The final result should look like this :



Hint : see to it that there can't be an electrical transmission between the different connection points - you can make sure by using a sharp knife to scratch off possible soldering tin leftovers on the PCB.