Select Line in the Add Feature panel in the top-middle of your OpenStreetMap interface. When the Line button is selected, the button will be blue, and your cursor may appear as a crosshair

Left click to add points on the line. The white node is the location you have left-clicked to add the point. The white line is the guide where the road will be, left clicking again will add another white node. By left clicking at appropriate intervals, we can trace the shape of Koala Street.

Finish by clicking on the pre-existing road, you know that your road will connect when the road you need to connect to glows red. Double-clicking on Wambat Street will connect your road with a grey node, confirming they are connected.

The line has no tags, so we need to add these in. We need to add the type of road Koala Place is. More information about how OSM classifies Australian roads can be found here: Australian Tagging Guidelines/Roads - OpenStreetMap Wiki.

In this example Koala Place is a residential road, we can use the Edit feature panel on the left side of the page. Click the Line section in the feature type. This will bring up the Select feature type, you may need to search the feature type. In this example, residential road is searched. You can find other types of roads classifications using this too

If the road has a name, it will need to be added into the name field under Edit feature. Save using the same method in [introduction to OSM guide]