Problem understanding Overload methods

I'm creating a class module that simulates trucks arriving and departing from the terminal. I would like some help creating the code for some overloaded methods. The first method named AddTruck should except one argument, the TruckID. also set the arrival time to the current time. The second method should accept two arguments: the TruckID and the arrival time.also set the arrival time to the value specified in the second argument. The explanations in the book I'm learning vb.net from are not helping me.

Your help is always appreciated. Thanks