Attach the USB Power to the Toggle Switch to the DC Motor.
Put that on the Lego Base and use legos to hold it in place.
Apply a small piece of tape on the Motor Arm so that the Gear can stick to it. This applies enough friction to hold it in place so that you can attach another gear.
Add the 2nd Lego Gear and make sure it is secured with Lego 1/2 Bush pieces.
We attached the Minifig to the Axle with the Brick Shaft (Lego Part Number 4258313) and then you can just attach it all to power and start it up.