Print parts. 
Glue together in steps. 
First the boat and pusher but glue through the hole opening at top of box. Be sure to face the way you want, no take backs.
Glue the oval and shaft togther, place inside box through one hole. 
Glue top of box on with words facing outside box. 
Next glue the axle and wheels together through the holes that holds the axle in place. 
Lastly find a rubber band that will fit around the shaft and wheel. 
Hoping everything works and you didn't glue your fingers together or parts to the box. You should have a moving box with two Benchys  going up and down.