On the Home tab, click the icon New to open Windows file explorer and browse to an urban network file. Ensure you are in the 1D Urban Networks section - this is the third section on this tab.
The 1D Urban Build tab also provides general urban network functionality, including the New icon.
Once started, your 1D urban network is shown in the 1D Urban Networks section of the Project panel. The simulation associated to your 1D urban network is also shown in the Project panel, in the Simulations section.
When you start adding components to your network, they will be displayed on the Map view, and the data shown in the 1D Urban Network panel. These will be blank initially.
Right-clicking the network name in the 1D Urban Networks section of the Project panel provides access to menus with options such as Set Active (if the network is not currently active), and Zoom to Network(otherwise). This is especially helpful if loading multiple urban networks at a time.
Note: Networks will be displayed in the map view and the Network panel if they are active. Other loaded networks are shown in the Project panel until made active. Changes you make will be made to the active network, and functionality such as saving the network all will apply to the active network. This is the same for river networks and urban networks.