the negative side should be marked with some sort of arrow or rectangle, i beleive its the longer terminal wire thats the negative

solder both negative's together and then both positives and have them facing away from eachother

you can solder these dirictly to the battery leads on the esc by cutting 5mm of the casing of, wra the terminals around the wire, solder and trim excess of, once done, insulate with electrical tape or referably heat shrink