Roads and bridges have their own category in the construction menu, and are built in much the same way as buildings. To build a longer stretch of road at one time, choose the type of road from the menu. Now place the cursor where the road should begin and, holding the left mouse button down, drag the cursor in the desired direction. The road automatically assumes the desired length. When building roads you should make sure that all buildings producing consumer goods have roadside frontage, so that the carts can transport the goods to either the warehouse or one of the marketplaces.

This is the only way to make certain that the goods produced actually get distributed to your settlers or are available for trade. Houses should also be built beside a road so that, for example, the doctor can visit the house. Make sure that the road actually touches the buildings. Otherwise they are not "on the street". Keep in mind that streets paved with cobblestones speed transportation by cart. Building bridges allows you to cross rivers.