How to make a wheel to follow a path?

Hello, I turn to the community of this blog to see if you can help me explain how I can run a wheel in the beam guide them in this simple assembly shipping, I can give movement on the track with angle but to give instruction that follow the curve, the wheel is fixed because you can only follow the first instruction.
my email is jmontalvoortiz@hotmail.com
thanks

1 Answer

Please could you also attach the parts to go with the assembly.