Mount the wheels on the geared motors. You may have a completely different set than I do here, but as long as it is geared motors that runs fine on a few volts, and some nice wheels, you will be al right.
When you have the wheels on the motors, cut one of the female-to-female wires in halves, take away some of the plasctic from the end of the wire, and solder it on. And do the same for the other motor.
Make sure no solder or wires touches the metal on the motor :)
Some wheels come with optional rubber tyres. It can be a good idea to wait with putting on this rubber, because if the robot is stuck, it can just slide, which is nice when testing and developing.