After you add devices you can add them to the topology. When devices are added you can connect them with link, so you build your network topology.
Now choose select button Add link, click on device From which you would like to create link and go to the device where link is connected.
Now you must select from which port to which port link is connected, when done click to Create link
When link is created you can see information about link. Just clic to small circle in the midle of the link and you will se information.