The DP123 is a humbucker.
So you need to solder the two "inner wires" and isolate them.
For DiMarzio this means:
Solder the green DP123 wire where the black wire is now (to housing / GND).
Solder the red DP123 wire where the white (or yellow) wire is now (HOT).
Solder the white and black DP123 wire together and isolate them (with tape).