Your motor assembly should fit snug in the bug body...
Passing the two wires through the holes in the middle - just make sure at this point that the end of the motor spins freely.
Zip-ties come in a plethora of colors these days... I think I'll stick with orange.
Zip-it... zip-it good... on both sides.
Bend your wires up and over the battery compartment.
Continuing into the indentations / wire guides on top.
Make sure that your wire makes solid contact with the CR2032 battery.