|| As shown in the picture (and as you did when making a plug), tear the two ends of the wire apart to make a V shape, and use a Stripper to strip the top of the wire bare.
Slide on the X (heat-compressible rubber tubing) onto both ends of the wire as shown. Only one side is shown in the picture, but follow the same process for the other wire.
Next, use the soldering iron to connect the two ends of the wire to the sensor. This can be done by adding some solder to the two end contact points of the sensor and to the bare ends of the wire. Subsequently, join the two together as shown in the picture, and allow the solder to cool, solidify and thus connect.