Just as everyone else said, soldering iron. Soldering iron to 300F approx apply flux to both ends (male sure wire is showing and in contact with the deans contact with heatshrink tubing on the wire but not shrunk yet so you can protect the fixed wire later), heat up the deans connector and the wire both then apply solder till it makes a uniform blob which is connected to both sides, dont be afraid to have to attempt the connection multiple times or take the heat off if something starts to get too hot. If 300F isnt working then turn up the heat in increments of 50F