Yes, the front and rear truck power pickup wires will have be tied together and connected to the decoder power pickup leads.
Set the loco's chassis on your workbench so the rear end of chassis is facing you. The truck's right side pickup wires will go to the decoder's red wire, and left side pickup wires to the decoder's black wire.
To figure out the motor's polarity get yourself a source of DC voltage (a fresh 9V battery will be perfect). Connect the wires coming from the motor to the battery terminals. If the loco starts moving backwards, reverse the wires and try again. If the loco now moves forward then the motor wire connected to the positive terminal of the battery should connect to the decoder's orange wire, and the other motor wire wire to the gray decoder wire.