Welcome to Episode 8. You are getting access to the Transport button on the ribbon toolbar.  

The roads built by your Engineer have been transporting resources every turn automatically. 
Land (or road) transport is shown with green slider bars on the transport screen.

Unlike road transport, transport of resource by sea (from a port) must have ships assigned to it. The transport screen is used to give these orders.  Each type of commodity that can be moved by water is represented by a blue colored slider bar on the transport screen. 

Use the arrows at the ends of the slider bars to control how much of a commodity your ships will move.