The DPDT switch in the diagram is basically like two of the switch you have being switched by one toggle. Just ignore one side of it. Without knowing what you're switching it's hard to say exactly how you want to wire it -- can I assume it's a power switch? In that case, you'd have the middle lug wired to the board and one of the outer lugs wired to the battery clip/dc jack. Or vice versa, it doesn't actually matter. With that kind of switch, the toggle is selecting which outer lug is connected to the middle lug, if that makes it clearer.