Oh, right. For an existing outlet, that's the right stuff that would be in there.
No, that's not what the white is. It's not "negative". The white is neutral, which is a midpoint at 0 volts between the two hot sides. So if you reeeealy wanted to use the term "negative", you could kind of use it for one of the two hot wires, if you want to call them positive and negative. There is 240V between those two, and that is all that the wall connector needs. It doesn't use the neutral at all. That is only needed if you have to have 120V for some reason, but the wall connector doesn't--it's 240V only. So just put a wire nut or electrical tape over that white wire to safely take it out of the picture.