The Engineer has completed building the port, which completes Episode 7.
Now that you have two ports (your capital and the one just constructed) your Engineer may build roads connected to either one.
However, keep in mind that the resources gathered from roads connected only to the new (non-capital) port must be moved by ship from the port back to the capital city. As you will learn in the next episode there are advantages to land transport.
It will be a good idea later in the game to connect all your ports (on the same continent) with roads to the capital. For now, ports are an efficient way to gain distant resources.
