Grab the rack part and two 25mm diameter goggly eyes. These can be press fitted into the eye sockets. The eyes should click and stay put. If they're too lose, use a bit of super glue to keep secure it in place.
To form the track assembly the base, motor tack and wheel track are bolted together with screws. Grab these parts and layer them to form the track assembly. Start with the motor track. Place the base over it. Make sure the mounting holes are lined up. Then, lay the wheel track over the base. Again, making sure mounting holes are lined up.
With the three plates now aligned together, insert a screw into one of the mounting holes – Going through the top track layer first. Slowly turn by hand at first. Lead the screw through and follow the tapped threads of each part. Use a screw driver to fasten the screw through the three pieces. Optionally use a power drill to speed this up once you get a nice flow going.