maximum of road

You do not have any limitation to add so-called markers to the map, which are identified with icons and can have a popuptext. If you want to change the underlying basemap on the other hand (like adding additional roads which are not yet mapped for example), you can do this by e.g.
registering an account at openstreetmap.org and submitting your suggested changes via their editor (our plugin adds a direct edit link to each OSM map – next to the attribution in the bottom right corner – which you can use to open the selected map in the OSM editor)